First, I wanted to thank everyone who gave me advice/support yesterday!
So today I met with my psychiatrist and explained my situation. I've also gained ten pounds out of nowhere and some of my clothes aren't fitting right now. So we discussed my options and she gave me a week's worth of buproprion (wellbutrin) to add to the lexapro I've been taking. She said it's more of an 'activating' medication, which will help with my energy and that it can also cause weight loss. So tomorrow morning I'll start taking it with my lexapro.
If this doesn't work or doesn't agree with me, the next step will be to try a mood stabilizer like lamotrogine. She said some people respond better to mood stabilizers than to SSRIs. She's a really great doctor and I trust her, so we'll see what happens.