First of all, if you are pregnant, congrats!
But you sound like you have a lot on your plate as far as stress goes...
Take the time to care for you, you deserve it and if preg., so does your baby. I actually experianced much of the opposite problem, Im a younger mother (20's), and my daughter was a breech baby.There are many women waiting till they"re in their 40's even 50's to have children. There are many postives, finacial stability, maturity, owning a home etc..
It does seem no matter who you are, when your pregnant everyone thinks your fair game for advice, criticism (and don't forget strangers wanting to touch your belly!) and no matter your age or weight or even ethnicity, there can be risks and complictations, (ty-sach, strep b and many others) Don't let that get in your way.
It sounds like you do need a new obgyn. My SIL and I had children the same time.She is close to my age but a larger girl (started out at size 18) and had many of the problems you listed,HpB, she also had a low blood count, ending up having an emergency c-section but both both her and baby are doing just fine. And you will be too.
We beat many of the steriotypes, my husband and I have been married 4 years this comming summer, steady jobs and income. My sister in law went threw all kinds of horrible criticsm with her dr. about not gaining too much then not gaining enough.. an old saying i've found true, mother knows best! Take care of you and yours, and Don't let anyone stand in your way.
Good luck and god bless : )