Hi J.! I think if you are posting the question and feeling unsure, you should probably switch. It is SO important to have a good, positive rapport with your OB and all the nurses during your pregnancy, as you know. You will be seeing them and talking to them a lot over the next few months and you should feel comfortable enough to ask any question, any time. As far as the due date and welcome package, some offices don't give those out until your 8-week appointment. Mine didn't with either of my daughters. You can get a due date from them over the phone, I would imagine. I used babycenter.com both times and their due date was exactly the same as my doctor's. However, that being said, prenatals are important - you should be able to just call whoever your dr. is and get a prescription as soon as you like! It's never too soon for those vitamins.
If you are feeling unsure about switching, you might want to wait until the 8-week appt. and see how you feel afterwards. It could be that you caught everyone you dealt with on a bad day - that happened to my best friend and she is very happy with her OB office now. It's really your call! I see you live in Brookline, and I don't know any doctors there personally, but I use Mt. Auburn Practice for Women in Watertown on Mt. Auburn Street - not TOO far from Brookline but not necessarily down the street. My dr. is Leslie MacDonald, who I love, and who got me two healthy girls after two higher-risk pregnancies (hypertension). Good luck with whatever you do!! Congrats about your pregnancy!