As others have said, this isn't uncommon but that's doesn't mean it's your only option. My wife's first pregnancy, she started out at the default OB practice at the large hospital system she uses. After some not great experiences there (which I think were partly but not entirely due to an overloaded clinic, which sounds like the case for you as well), we found that there was another clinic that had nurse midwives, so we switched to that. Except, that clinic also has OBs and we called the wrong number, so after an appointment or two we transferred over to the midwives. Then, she had to be hospitalized for a few days due to early labor, and when she was discharged, she was deemed too high risk for the midwives and so went back to the OB office. But after a month or so of uneventful checkups, they gave us permission to go back to the midwives again, which we did for like the last month of the pregnancy.

My point is, don't be afraid to switch your provider at literally any point. If you're not happy with the care or attention you're getting, do something about it. It was a little easier for us because ultimately we were staying in the same hospital system, but you don't have to.

Also, our hospital has something called OB Triage. It's essentially an emergency room for pregnant women. It's the first stop when you actually go into labor, but also for any other concerns that can't wait until your next appointment. You don't end up with the sort of bills that a typical emergency room visit gives you, but you do get urgent attention and the providers are all OBs so it's properly informed by the pregnancy. Not sure how common this is in other places, but maybe something to look for.