A.S.
I don't think you're overreacting at all. I think it's definitely time to find a new doc. I'd also bring up everything you told us here, or write it up in a formal complaint and send it to the doctor's office.
I'm not sure where you are, but we see Dr. Belzer and love him. His practice is called Pediatric Professional Association (http://www.ppadocs.com). We've seen some other doctors there as well and have been very happy with them all. We've never had any trouble getting in either. They have walk-in sick hours every morning, and during the cold/flu season they are open on Saturdays.