Can't relax or 'let go' around boyfriend?

I've been with my boyfriend for a year and one month after spending three years crushing on him. We're great together, says everyone, and we are. We don't fight, if there is a disagreement we talk it out. He does things for me and gives me things not because he expects anything in return but because (he says) "he loves me".

My problem is, because of a terrible track record boys and just life in general, I don't know how to meet his some of his needs. He kisses me, cuddles me and all this other stuff, but I get so anxious returning the favor. He knows what I've gone through, and so I feel like even though he says it's okay and that I need to go at my own speed, it still bothers him. And if it doesn't, it bothers me. I want to show him that I love him, not just through saying the three words, but giving actual affection.

Any suggestions or advice on how to let go and relax around my boyfriend, so I give him the love an affection he deserves?