plus size mamas

Bare with me, this might be a little long. Flashback to 10 week appt... doctor told me we would have our gender and anatomy ultrasound at 15 weeks!! i had to reschedule for 17 weeks because hubby was out for work. so we went into the appt with our doctor and she said because ive gained NINE LBS! since the start of my pregnancy its too much weight and we wont know the gender of iur baby til closer to 22 or 25 weeks. why did she change her mind and why am i feeling bullied about my weight gain? with my daughter at 17 weeks i had already gained closer to 50 lbs and they gave me an appt at 18 weeks to find out the gender. i was heavier then than i am now and yet we cant know til 22 to 25 weeks because im too big???? im baffled and annoyed i just need to know a reasoning for it. it doesnt make sense to me. she promised by 15 weeks and changes her mind at 17 weeks?...