I think Tessa had this small belly in the earliest videos already. It is just her body type, she is not the skinny type. Petite and slim, yet very feminine and curvy, overall very healthy. Weight goes up and down and it is hard to tell how recent photo shoots are or if they even are published in any chronological order. But still she seems to have periods of working out a lot (working on sculpting her tush, midriff and legs) and did take some breaks as well, for personal and family reasons. And then she might have gained some weight (at all the right places). Just a combined pic from 2013, may not be the best pic to illustrate.