Really need advice/tips to lose weight!

I am only 20 years old, I have 2 beautiful kids. My first pregnancy I gained 80lbs and Dr’s couldn’t tell me why so we never ever found out what hapepned. I weighed 175 before my first pregnancy in 2017! After birth I weighed 260.... I am so embarrassed and disgusted with myself. With my second pregnancy I had gestational diabetes and had a controlled diet with insulin. I now weigh 245 after birth. I want to start BC soon also. I am 3 months pp and the diabetes diet really did help me, and I want to start again, but is there anyone else that lost over 100lbs and has any tips for me? Thank you so much. Just want to feel beautiful again...