My boyfriend doesn't let me do nice things for him

Okay the title isn't entirely correct, but for example I like to surprise him with small token gifts or home made cookies and when he's sick I will go above and beyond to make sure he has everything he needs and wants to feel better. For his birthday I wanted to make him a cake and take him out for dinner and go karting. And I always offer to pay and help him and his family out. But he says I do too much and it makes me feel uncomfortable. I do kinda understand where he is coming from but it's not like I'm expecting all that in return. I'm happy with what he does for me, but I'm a very generous person and I like to do extra special things for him because when I'm in a relationship I go all out. My boyfriend is the most important person and I want him to be happy - doing these things makes me happy. So I guess I'm selfish. I care more about doing these things to make my self happy than him being uncomfortable. It sucks. But we can't break up because "I was too nice" that's just stupid. Basically I feel like I'm not giving my all to the relationship because he doesn't let me.