I have no sex drive 12 months PP

I had our son just over a year ago, and I still have zero desire to have sex. Mayyyyybe once a month I’ll be kind of in the mood, but it’s rare. I have no energy for it anyway. I do basically 100% of the childcare. When I work on the weekends and my fiancé stays home with the baby, I resume doing all of the childcare once I get home even though I’m exhausted. I have to ask my fiancé to change a diaper, he won’t take the initiative to do it himself. I do 100% of the cooking and cleaning up after a meal.

My fiancé wants sex often, but we can only have it when the baby is asleep so he pretty much goes off into the bedroom or something and waits for me to nurse our son to sleep. I usually only have sex because I know my fiancé needs it and I don’t want him to feel bad about himself, but lately I can’t even pretend to be into it. I have laid there like a dead fish more than once recently.

I guess I’m just frustrated that I have no desire to have sex, and that frustration is made worse because of my resentment toward my fiancé.