Congrats, Noodly! Also hugs (if you don't mind), because I felt exactly the same way when I graduated. In my experience, though, college had a lot better of an atmosphere than my high school did. Of course all schools are different, but I'm confident you'll do just fine
And I have the same problem with donating blood. Though in my state it's that the minimum weight for people under a certain age is higher, and I don't consistently make that weight. I'm not a huge fan of needles, though, so I'm a bit relieved to not have to face a moral-vs-personal-comfort dilemma!