My son was 10lbs 3oz and yes I had to have a C-section, but only because I was contracting for 2 weeks and not progressing at all. That was NO fault of my weight, but everything to do with having a giant baby and stubborn cervix.
I had NO GD. NO hypertension. NO nothing and I was treated like CRAP by my OB's office until I complained and made them feel like crap. I'm only 5'6"ish and I've been a size 18 - 26 most of my adult life. I'm more active than most itsy bitsy "straight size" women. I was still hiking the Arizona desert and mountains up through the middle of my third trimester. When not pregnant, I ride horses in several disciplines. Do I feel sorry for myself? No. I compete in plus size pageantry to spread the word that being overweight doesn't necessarily mean that someone is unhealthy, lazy, or useless!
Newsflash: Plus Size Preggos have extremely healthy babies EVERY DAY! My current OB has gone on record to say that she sees more GD in her size 2 health nut patients than in her size 14+ patients. Case? My sister developed GD which has turned into full blown Diabetes now and her son is 6 weeks younger than mine. She's a size 8-10.
So... Ignore the fear mongering and seriously work to enjoy your pregnancy. Find another OB and complain endlessly about the ones working to stress you out. Can't switch? Do what I did. Tell them "Great! Now instead of trying to fat bash me, tell me what I can do RIGHT NOW to have the healthiest pregnancy possible! Sadly I can't wiggle my nose, snap my fingers, or click my heels to magically and immediately shed the excess weight so let's stop attacking me like I can and be informative and productive, mkay? Glad we're on the same page now."
They get taken aback and shut their mouths pretty damned quickly.