Loss of sex drive

It been 9 months since my baby and I am breast feeding. We have been going through stressful times. I have zero sexual desire. I have made so many excuses now that he knows I don’t actually want to do anything that’s why I have excuses. I feel like it is putting a drift between us since I am always saying no. What do I do? I do want to be sexually there for him, I just don’t know what’s wrong.