Weight problems

Soo i been dating my boyfriend for 5 years now when we first met  i was weighing 115.. So for our first 3 years i staid my same waight. I have been switching birth control since dating him  and last year i decided to switch  birth control  and the last birth control method i used was the implant( worst mistake for me)  i gaind 30 pounds .. I weigh 145 pounds  :(   it made me  eat like crazy and supper tired.. I never thought of gaining so much weight and as a 21 year old i feel gross for leting my self go..  I have thigh stretch marks and the side of my hips have stretch marks as well 😔...  What do you guys recomend  for stretch marks ans what do you recommend  for me to do to loose all this waight i have gained???