18 year old female 350 pounds. Need to lose weight!?

im 18 years old and just got married on june 11th. I weigh in at 350 pounds. my heaviest ever. I have always been heavy but could usually keep it below 280. I have PCOS and find losing weight REALLY hard even when i do eat right and exercise. I really want to lose weight ( it doesn't matter how long it takes, i just want to be healthy!) because i do want children in the future ( about 4 years or so) and my gyno said the more i lose the better chances i have at conceiving. I want to be thin and healthy. Enough is enough. i currently don't work and have graduated from school so i do have alot of time while the hubby is at work. at 18 i shouldn't be worrying if im going to have a heart attack or be told my B/P is so high i could have a stroke. any tips? advice? anything ( except sarcastic comments) is helpful! Goal weight is 180. Im 5 '10