My DD2 is 10 weeks old. I'm breastfeeding almost exclusively. Now I'm 10st 2lbs and my pre pregnancy weight was 9st 7lbs. I wouldn't be so anxious about my weight apart from it seems to have stuck for the last five weeks and I can't do up my trousers! Is it because I'm not eating enough- I'm back exercising (jogging and yoga) and according to MFP eating 2000 calories a day. All I'm worried about is that if I don't lose the weight it will be there forever!
Your DD2 is only 10 weeks, it's perfectly normal to still have the weight on. There's some info on losing weight whilst breastfeeding here. A lot of breastfeeding mothers find the weight comes off in dribs and drabs rather than at a steady pace. For me it was at 3, 6 and 9 months.