Lack of libido help

So I have a horny ass bf and he wants some all month every month. But I've never had a high libido, I didn't really want any thing at all till I was 17 or 18 (I'm 20 now). But I am very horny my ovulation week and very dominant but i don't want anything i just want to mess with him the week before my period. Then the other two weeks I don't want anything at all which is frustrating for us. I want to do stuff but its a struggle. I also have bad bloating and acid reflux problems so my stomach issues get in the way as well. I just want a good sex life. I only really really like stuff a couple times a month. What do I do????