Hello ma am and welcome. Breast feeding/nursing is a natural contraceptive and although not a very effective one, in many cases it can help prevent conception. It is something created for God to promote spacing between children, and so they are not born and conceived back to back. Hoping this alone would prevent conception in your case. Your symptoms could be related to the hormonal changes your body is experiencing and of course it is way too early for your tummy to grow due to pregnancy. You can continue trying to lose weight, your body should allow it right now as pregnancy is not a close possibility. Hope this helps. Best wishes.