Is this normal for a new mom ?

I’m 30F and really looking for some advice from anyone who’s experienced something similar.
My son is 18 months old. Since he was born, he has never slept for more than about 3 hours at a time. Even now he wakes every 3 hours for a bottle. I’m also a very light sleeper, and because we co-sleep, I wake up with even small disturbances. So I’ve been living with fragmented sleep for a long time.
Lately, I’ve become increasingly worried about how I’m feeling mentally and emotionally.
I feel like I’m functioning, but I’m not functioning well. My attention span has become much shorter, I struggle to follow conversations, and I make more mistakes at work than I used to. Sometimes I can’t remember what I did yesterday or even earlier the same day unless something significant happened. I also find myself searching for words or saying the wrong thing without realizing it until later.
Emotionally, I don’t feel like myself either. I’m constantly on the verge of tears. The other day my manager casually asked, “How are you doing?” and I immediately started crying. I love my son and my husband deeply, and I’m genuinely grateful for them, but I rarely feel happy anymore.
I’m trying to understand whether this could all be related to prolonged sleep deprivation, burnout, or something else. Has anyone experienced something similar 18 months postpartum? If you did, did things improve? Did anything help? And did you end up speaking to a doctor about it?
I’m planning to get checked by my doctor because it’s starting to affect my work and daily life, but I’d really appreciate hearing from others who have been through something similar.