Usually people gain weight when setting treated for depression. But everyone's different maybe it's a side effect from a medication your taking.
Are you eating less? If yes then is it because you dot feel the need to eat, that your stomach hurts, or that you just can or won't eat?
I'm not sure what you're asking us. Has the weight loss left you at an unhealthy weight for your height and build? If so, you need to see your doctor immediately.
If you are happy about the weight loss and find it beneficial to your health, consider that a very nice side effect.
Some ADs DO affect our weight, but usually not to extremes. You are not losing weight at a dangerous rate. 4.5lbs a month is a safe and healthy rate.
My concern would be that you only weighed 105lbs before the weight loss.
I think I would still let my doctor know if you were not intentionally trying to lose weight. It's safer to alert your doctor to any changes while on a psychotropic med.
Peace
Greenlydia