J.T.
I say GO FOR IT!!! My story: My normal weight is around 135-140 pounds, but I became fat and lazy when I got married. I weighed 172 pounds when I got pregnant. I gained a moderate amount of "real weight" and A LOT of water weight. I weighed 217 pounds on the day I gave birth and lost 30 pounds within 2 days. I was down to my pre-pregnancy weight within a month without any effort. Since then, I began working out and eating right and am in the best shape of my life. I am a fit 135 pounds and feel great. My son is 2 1/2.
Bottom line (IMO) is that you go for it, UNLESS your doctor advises against it. Begin exercising and eating right while you try to get pregnant, and continue doing so throughout your pregnancy. Then, you will hopefully have the momentum to lose any extra weight you need to once the baby is born.
GOOD LUCK TO YOU!!!