East side sun will definitely not be enough to overwinter a tomato plant in our area. If you could get it in a south side window WITH supplemental light, you might get more fruit, yet, but I'm afraid you're fighting a losing battle to get much more than what you already have. You're plants will likely get paler and leggier, and the fruit smaller and smaller.
If you had a south facing bay window with a glass top, you'd likely be in pretty good shape.
USDA zone 7b/8a (depending on the year and microclimate
), AHS heat zone 8-9, Eastern Crosstimbers/Grand Prairie ecozones