It is always a good idea to check with your dr before doing exercises, walking is generally good and don't forget your kegal's, light exercises are good, if you belong to a gym,or call a gym they can give some information, it is generally fun working out with other pregnant women and you can learn more about your breathing while working out and they generally keep it low-key, if you have the time. I did not gain that much with my pregnancy's either, the main thing is is to eat properly even though it is difficult as you cannot help but to go with those crvings sometimes, mine was brownies and pudding. The main thing is is that you enjoy your pregnancy!