Good heavens :) Cut yourself some slack! First year of uni is hard. You just moved out--you may have left the state, or the country. So, you're learning how to live on your own in a different environment. That's tough. You haven't really found your group of friends yet, or your major. That's even harder.
Your greatest hope is the same greatest hope many people have. And believe me, a lot are in your same shoes at the moment.
I think you're just going to have to put yourself out there. You're mentioning that you're never taken into confidence, never asked to go anywhere, etc., but do you ever ask that of other people? Give it a try. You have nothing to lose and the world to gain. People do seem to form groups and circles, but it's been my experience that many people love to meet new people--and befriend them. Try joining a few clubs, or going to guest lectures, and debates, and things you enjoy. You'll be surprised at the people you'll meet.
I don't think you're boring--I don't really find people boring. I think though, that you're spending too much time thinking about what other people think before you approach them. Or how you're perceived by them.
Try this: like people first and show an interest in their lives. People like people who care and who remember them. And just start talking. Don't hide yourself from the world. I'm sure you're a wonderful person.
It's not because you're not into substances. Frankly, I find drugs and alcohol to be unbelievably stupid. I typically do not drink. I'm also fairly popular. I refuse to drink unless I'm with close friends, and never a lot. Because I never want to lose control. People have realized this, so they don't bother usually inviting me to large parties, but I know if I showed up I'd be welcomed regardless. They just don't want to keep inviting me to something they know isn't quite my cup of tea. Which is fine.
You mention this: "How can you trust people if they don't trust you?" Well, you have to risk it. Nothing ventured, nothing gained. If you don't trust someone, or give them a chance, you have nothing. And you can't wait for the world, and friendships, to come to you. Sometimes maybe they might, but generally, not all the time.
So start it slow. I'm sure you know people with common interests with you. I love art, so I'll occasionally ask people if they'd like to go to an art gallery with me. Or just downtown to hang out. Or for coffee. Or just randomly start talking to my suitemates in the hall. Just talk, and show people who you are.
Regarding your instructors, I've found that in university you're marked more harshly. Take an essay or an assignment you feel you should have gotten a better mark on, and go talk to your prof and ask them politely why you didn't and what you can improve next time. It's good to receive that kind of feedback. Most profs and TAs are quite considerate and more than willing to do this.
It's okay to not know what you're doing with your life. It took me a full two years of uni to choose my major. I don't know what I want to do with my life. But I'll figure it out as my life progresses. You're in school. So you're doing fine.
Don't be ashamed of being in therapy. At all. There is no reason to. Your R.A. was concerned--they care. That's a good thing. I definitely know what it's like to not want to get out of bed...I've had many mornings like that myself. But you just have to keep going, and build the life you've imagined. You can do it. Make it a beautiful one.
Don't take the fact that your suitemate is living with someone else next year too hard. I have several friends whom I considered living with, and when I filled out the form, I decided I wanted to live with someone I didn't know, even though I'm upper year. It's simply because I felt like our living styles weren't as compatible. It has nothing, absolutely nothing, against them as people. If your suitemate truly hated you, she would have left long before now. It's okay. Next year you'll have the opportunity to meet someone new...and you may be pleasantly surprised.
I know you feel overwhelmed, and that you're disappointed in yourself. But you're treading water. You haven't drowned in the newness of university and gone back home, you've stuck it out and although I can't know the particulars, from the sounds of your post it seems that you're doing okay academically. So you're fine. But you can make this better as time goes on.
Please don't be so hard on yourself. You're really doing fine. And you will make friends. Show people who you are. Don't hold back.
I wish you all the best.