T.,
Breast feeding helps you lose weight faster bc you're expending more calories than you're consuming (hopefully). Also, my understanding is it takes about 3 months for your body to adjust to NOT being pregnant so don't expect any significant weight loss during the first three months (aside from the baby, of course).
Keep in mind that it took you 9 months to put on all that weight (I gained 65 lbs with my first too....) and is going to take you at least that long to lose it. Remember that even "losing weight" is a misnomer bc the fat cells don't actually disappear, they just deflate and so gaining it back is so easy later on. Certain parts of your body will be changed forever (your hips mostly) and keeping a pooch off will be more difficult. The best solution is lots of exercise (my poison is running, ellipitical rider, and weight training), and eating healthfully (celery! gotta love food that requires more calories to chew than it contains). And don't get discouraged!! You CAN do it.
If you're a member of Southeast Christian, take advantage of the gym and various exercise classes they offer.
If you can't get to any gym, try a rigorous workout video that you can get your baby involved in with you (leg presses using baby, stretching while baby watches from the floor below).
Stretchmarks- no cure for that. Unfortunately, those are hereditary...your predisposition towards them you can thank your mother for. They can fade with time (yay!), altho that too is based on genetics....so how did your mother fair? My advice (and I am so being serious here), just don't wear midriff-bearing tops. My son has a 40-something mom who drops her child off every day and has bad stretch marks yet still finds it necessary to dress like brittany spears....
Ultimately, your body is changed forever and there's a pound or two you'll never be able to lose...but you can do it! Just don't get discouraged....remember that the best weight loss is gradual. More than a pound or two a week and not only is it hard on your heart muscle, but it probably won't stay off.
GOOOOOOOODDDDD LUCK!!!! You CAN do it.