Hello & congratulations on your baby girl. From what I have been told when you return to exercising you should stick to low-impact stuff like walking for the first 12 weeks, longer if you are breastfeeding. The high impact stuff is not good for b'feeding mums and you basically have to strap your bb's down tightly with a very strong sports top or 2 if you are doing anything remotely jumpy or bouncy. Also exercising too hard can reduce your milk supply - it puts too much stress on your body. Plus there is the dehydration factor - you need to drink loads before and after.
Try not to put too much pressure on yourself to get back to your pre-baby body so soon. It will happen..just not over night. Enjoy your bubba and good luck!