I don't have a great sex drive!

I don't have a great sex drive me and my partner have sex 1/twice a week all depends on my health I have cystic fibrosis and diabetes also have severe tummy aches and it tyres me out i caught pneumonia back in July and since then it's a total effort I love my boyfriend so much and we have incredible sex but when I am feeling rough I just cannot be bothered and I think it's getting to him but he says it's fine my health comes first I just feel like a rubbish girlfriend sometimes. Is there anything I could try to get my sex drive up?