I recently got a physical, there was some weird stuff in my pee and the doctor really wanted me to get a blood test, like immediately, like next morning. Now, I absolutely hate getting blood tests and I even tear up at just the thought of it. I don't like needles, but I don't think that's the root of my fear. It's mostly the fact that I just don't like the thought of blood and veins and stuff, how it takes much longer than like a shot, and the light-headed feeling I get (and also the fear of actually passing out).
I have gotten one before. It went relatively ok. Yes I was incredibly nervous but I was fine if not for some light headed-ness. I thought the second time would go the same, if not better. I was wrong. Walking into the place I felt very nervous but otherwise fine. I had some manga to read on my phone to distract myself, which I was reading as the nurse stuck the needle in. Now, last time, there was only the initial prick of the needle going in and then I felt nothing. But this time, I felt it more after. I think that was because, according to my dad, it looked like she missed the vein and was moving it around to try and find it. Very soon after the needle was stuck in, I started to feel quite light-headed (and I think it was when she actually found the vein). I told the nurses and they took it out.
I still wanted to try and get it over with, so I went to a separate room where I could lie down to try again. But when I saw the nurse bring over the equipment, I kinda started uncontrollably crying. I decided to do it later, calmed down and left.
Now for the after. The arm where they actually punctured, still hurts. If I move it in a specific way I feel a sharp type of pain (although it's not too bad). Everytime I even start to think about the fact that I'll have to still get the blood test soon, I start to tear up and soon start actually crying. And I feel very nervous too. Distracting myself with anime or something has been keeping me going throughout the day. I also don't have much of an appetite, but that may just be because I'm just really stressed or because I've been kinda sick the last few days. And I think the fact that I'm eating less, would just worsen the lightheadedness.
I really really really don't want to go back and actually get the draw. I know it was probably just a bad stick and that it'll be more like the first time, but I still can't help but be so nervous. I know just need to wait until I'm more mentally stable, for lack of a better description, but it just feels like I never will, or it'll at least be a long time (because I feel pretty much the exact same physically and mentally than right after I left). But I'm nervous because my doctor was so adamant about me getting it soon, but I just don't think I can. I just don't know what to do. I guess this was more of a vent, but it you have any advice I'd love to hear it.

I get blood tests done pretty often and one thing that I always tell everyone... be hydrated!!! It's super important. It helps the blood draw go faster and it will rule out dehydration for any test results. Being hydrated could also help with feeling lightheaded, but it also might not.
If you are not required to fast for a blood test, then make sure you get something to eat. I always feel the dizziest after tests that I have to fast for, so food is important if you're allowed to eat.
And for that pain? Some are just less experienced so there will be times where the person drawing your blood just... sucks at it. Not much can be done about that. But being aware of your body could help you out. I know that in my right arm, the vein is harder to find and the spot they typically draw from there happens to be right near a valve in my vein. They end up having to dig around in my right arm and I end up with a pain similar to what you're describing. Not fun stuff. So whenever I go in to get my blood drawn, I always tell them to draw from my left arm. I've had no troubles with my left arm. If one arm consistently has troubles, then just have them use your other arm. Or maybe you need a smaller needle used? Maybe needing numbing in that area first? Whatever it is that you can find out about your body, remember it, and let them know.
As for nerves... it can be hard not to be nervous. Distractions and breathing exercises can be a huge help. And if seeing the needles and/or equipment worsens your nerves, you can always try keeping your eyes shut. Don't be embarrassed by needing to do something that can be seen as childish if it helps you get through it.

Hope this can help!