I’m lazy during sex

Ok so I don’t know what to do about myself but I need help. I’m a single mom with two kids and me and my boyfriend have been together for about 5 months now. My kids have aged me and although I’m only 23 my sex drive is nothing of a 23 year old. I feel sexually attracted to my man. He’s so sexy and has such a nice body and is very well prepared down stairs. He gives literally the best head I’ve ever had and I have ZERO complaints to our sex life but I never feel like I just wanna pounce on him ya know? Sometimes at work we’ll sext and I’ll really want it but by that night when we’re laying down I just wanna go to sleep. Or if we actually do start having sex I never want to be on top bc I don’t want to have to do any work. Being on top used to be my absolute favorite. I need help. I know my boyfriend loves me but I would hate for him to eventually get bored and want more and try to get it somewhere else. I’m all about pleasing my man but my body doesn’t care for it anymore.