My friend. There are always new opportunities that await you once you choose a a heavy choice.

Did you consider breaking up? Breaking up is hard, but maintaining a toxic relationship can ruin your life.

As the saying goes, "When life gives you weeds, pull the weeds out."

Off and on relationships don't last. They just don't. And if they somehow do, they're incredibly unstable and usually unhealthy. It's really not worth your time.
I know it's really hard to let go, but at this point, you desperately need to. From my understanding, she doesn't share the same feelings for you, but she's scared of being single, hence why she keeps coming back to you. This isn't good for either of you. You both need someone else.
In my opinion, you need to let her go. Don't take her back again. Give you both time to heal and move on.
You will find someone who doesn't think you're too clingy, someone who will be there for you and care for you. You'll find that person, but this girl you're with now isn't that.