Weight gain

Hannah🌸 • PSOC/endometriosis sufferer with a past ectopic pregnancy, now currently pregnant with a baby boy💙
I just turned 6 months pregnant & have gained 20lbs...my midwife told me that's too much weight & wants to put me on a diabetic diet (I'm not diabetic nor have signs or symptoms of gestational & glucose levels are great), eat more protein to keep me full longer & to start walking. 
Is 20lbs really a lot??