So sorry to read this. But as someone who is MUCH older than you, I hope I can say that it will get better. You are so so young. And here is a little secret, I was a virgin until I was 24! So, at 21 I was a lot like you, I can relate to your feelings. I think that I soon as you break that barrier, meaning have your first relationship, even short one, it will start to get easier. Beginning is horrible always so be prepared, but be also brave. It's not easy to find someone you will love and who will love you too, granted, many of us feel the same. So be prepared for some short and not so great relationships in life, but it's important to start! Everyone was rejected in life several times. It's though but it happens. Each experience in relationship will make you stronger.
I am so sure you are not unlovable, probably just shy and insecure.
And you are not alone, look at this board, there is so many of us who feel the same.
You so deserve someone's love, remember that. Never ever think you don't.