Cant get the weight off!

Ok so i have been at this since Aug and i am only down 7 lbs. I have been heavy for years and enough was enough when i found out i was preggo again in Nov 2009 and i weighed in at 261 lbs. I had just had a baby a year earlier and had gotten down to 220 so i exactly 1 yr i put 40 lbs back on. My youngest is 1 1/2 and I been able to keep off over 40 lbs. I am at 213 right now and have been trying for 5 months to get under 200. I was at 220 in Aug and i am stuck between 220 and 212. I need help. I think my body has hit a plateau???? Could that be it??? I am counting carbs and have been able to get off about 7 in the last 2 1/2 weeks. Counting calories just didnt work for me. I had Gestational Diabetes with my last 2 pregnancies and was on a low carb diet during the pregnancies to control my blood sugar with my 3 yr old i only gained 13 lbs (went from 241 to 254) and after i had her i was down to 220 in 4 weeks. With my 1 1/2 yr old i was 261 and delivered her at 261 so i gained nothing and went down to 220 again 4 weeks after she was born. So my dr and i have some to the conclusion that low carb works for me. We also think i have hormone problems and that is why I am trying to get it off. Please help!!!!!!!