Medication Weight Gain??

I suffer from pretty severe anxiety. I feel like I have started carrying a lot of water and bloating in my stomach. My weight has increased and that devastates me. I think some medications I take may be the culprit. However, I only notice a difference in my stomach. My arms,legs,hips look the same. I eat a low calorie low fat diet and work out so random weight gain doesn’t make sense. Do medications cause water retention or bloating? Has this happened to anyone else?? It’s making me crazy!

I take:

Gabapentin/Neurontin

Zoloft

Lithium