First I must apologize cause this might be a bit long, but if you have the patience, please give me some advice cause I've been feeling a bit lost lately. If you want to skip to the problem, it starts with the third paragraph.

So, I never really had a hard time making friends, as far as I can recall I always had at least one person I'll call a "friend" no matter wherever I'm put in. Anyway, I'll tell my history of friendships first as it might help clarify the situation. From 2nd grade to 6th grade, I had one best friend who was the total opposite of me; we had different preferences, personalities and we absolutely had no commonalities but still, I loved her (not romantically) and we were really close. At the end of 6th grade, I had a bit of um... existential/identity crisis (which extended for two years), for whole two months during summer, I tried to find myself. There I realized that throughout my friendship, I never really had the chance to think of my own view of things, it was always me copying my friend, so by 7th grade I was aware that I was empty. My persona in my family is basically me trying to do anything that was expected of me and my interests was just me trying to catch up with my friend. I tried to push that thought at the back of my mind and in 7th grade, my friend and I had been placed in different classes and there I started to discover myself a bit. I looked at myself not in comparison to my friend but solely to myself, and removed things that I know are not something I enjoy but had to try to enjoy because I wanted to fit in. Here I became aware that I was an introvert (though I didn't know that there was a term by that time) and I most of the time spent my lunch and breaks watching anime or reading books alone which I thoroughly enjoyed, and occasionally went with my best friend and my other temporary friends in that class. I've grown interested in science and basically trying to gain knowledge while my best friend focused more on her social life. We grew apart but still chats every now and then and although now I wish we can grow closer, I don't know how. Anyway, moving to 8th grade, it was my first time to discover that people with the same interests as me actually exists outside the internet, and needless to say, we grew attached to each other. I really didn't think that people that I can talk to for hours and hours actually exist. I love the group and still, we're close to each other and they helped me grow as a person. By 9th grade I had to move, but my friends were really great that they didn't let me feel the distance. In my new school, I created new friends, but I never got close to the point of opening myself to them. I am currently in 12th grade and here are the things I have observed that really worries me.

I realized that every time I talk to people, especially to my friends, despite how I enjoy our time together, I often feel so lonely afterward. Not the lonely kind that I miss them, but I was lonely because I felt like I couldn't connect, and I wanted to just leave the friendship and never really talk seriously to anyone again. I honestly prefer being alone, but I am aware of the benefits of having a good social life, but still, most of the time I feel the need to catch up with them, maintain my relationships but I honestly dread the aftermath of opening up because during the time I talk to them I genuinely love the conversation but it's always after that I wish I hadn't talk. All of the people I've been friends with are great and almost everyone I talked to encouraged me to continue the conversation so I don't think that there's any factor that would make me lose confidence either. (Although I do suffer every now and then from "belittling myself" or so my friends told me, which I don't think is correct cause I try to see myself for what I actually am) I genuinely adore my friends and am attached to them, but most of the time I just want to sever all the ties I have with them and just become friends with someone for a year. I think the problem lies in the fact that I am a bit wary that I might get boring, or because I do know the fact that I am getting bored with myself since being a senior, I have no time for self-improvement and spends most of my time studying for college entrance exams, but I don't know, that might not be the reason cause even during the time that I had a lot of new interests growing, I always felt the need to just stop interacting and make new friends elsewhere, despite how great my relationships are with my friends. Currently, I feel so alienated from everyone despite being with them, and I honestly don't want to bother anymore but I don't want to ruin anything, plus my friends are really great people and I also don't want to leave them. So there's that contradiction and now that I'm entering college, I dread the fact that I know that I would become friends with my roommate, no matter what kind of person she is, and I honestly don't want to feel this way to anyone of my friends cause it corrupts the emotions I have with my memory of them, and it limits me. So if you have any pieces of advice or even criticisms or anything that could help, that'd be really great. Thank you.

Don't be afraid of people being disappointed in you. There are more important things than getting hurt. This is just my opinion, but I think the problem is that you're always wanting to change yourself and/or conform in order to feel accepted by other people or to relate to them. It's actually admirable that you tried to resist that initially, though there's still that nagging feeling. This is where your loneliness stems from, because no one ever knows how you truly feel - you never actually tried to tell anyone or make them understand your real feelings, so you feel alone.
Don't lose yourself for it. Do what you want to do. Of course, having friends is nice, but don't force yourself to do it. People come and go. Just because you don't talk to other people much or start a conversation doesn't mean you'll never have friends.

A great man once told me “ don’t be afraid to rock the boat, if someone falls out they wasn’t meant for your boat to begin with.” You shouldn’t fear being different, being different makes you respectful. Don’t change for other people and don’t be someone you’re not. You will soon enough find people who are meant for your boat, just continue being you and don’t change for anyone. Don’t fear what people may think of you, allow yourself to be yourself and never change for others.

Could you elaborate on what you mean by not being able to connect with your friends? Do you mean you have different interests or you don't feel like you can tell them certain things? Why do you regret opening up?

Your last couple of sentences also confuse me. (From "I dread the fact" to the end) Are you saying that you're scared that you can make friends with anyone, regardless of what kind of person they are?