High needs baby is overwhelming me

I’m a SAHM who’s alone with my kids for the majority of the day. My second baby (9 month M) is extremely high needs, and needs held almost 24/7, doesn’t sleep at night unless held, if I try CIO or do not give in to his crying he will throw up everywhere, and a couple times has almost aspirated, he will throw himself back and hurt his head.

We’ve taken him to doctors, nothing is wrong with him and they have just classified this as “high needs” and “clingy”. But I’m going insane.

I can’t do anything, I can’t sleep, eat, go on a drive or walk because he doesn’t like being strapped in. He likes a baby carriers but he is giant and wears 24 month clothes already and it gives me migraines from the weight in my shoulders. I’m afraid I’m going to start resenting him.

I also have a 2 year old daughter (26M) who thankfully is independent but I feel guilty because I can never play with her, or give her 1 on 1 attention, even if she is meh on it.

I’m on medication for PPD,PPA, and PPOCD. I’m in therapy. Thank you to anyone who listens.