Excessive weight gain during 1st trimester?

This is my second pregnancy and I'm 50 lbs heavier now than with my first child who is now 2 years old.
I had my first OB appt a few days ago and when I stepped on the scale I literally almost fainted. I have never been this huge in my life!!! I'm ALWAYS hungry and I don't have any nausea whatsoever!!! I've never really experienced "morning sickness" 🙌🏻🙌🏻 but I'm just packin on the pounds. The doc says the max I should gain during my pregnancy is 15 lbs or else I'm being put on a diet to avoid gestational diabetes!!! Light exercises is ok per Obgyn. I'm mos def gonna hit up the gym.... Soo to cut to the chase here has anyone gained a ton of weight during your 1st trimester and if so what did u do to maintain or shed a few lbs that was healthy for you and baby?