Single Mom to 9 week old

I’ve reached the point where when I do fall asleep I can’t hear my lo crying. And I feel like a terrible parent. Idk if it was the shots or the age sleep regression but lo isn’t sleeping well and fighting it constantly. It was 3am and he just fell asleep and my mother texts me and tells me he was crying (in the same room as me) for a “while” whatever that means. He was safe and fed and changed and swaddled and I didn’t hear it, a half hour after that message I woke up and he was sound asleep. I’m just exhausted and I don’t get any type of help. I hope it gets better.