I was on 15mg Lexapro and things were okay except that I'd have one huge swing upward from around 10am to 3pm and then I'd crash really badly (depressed, tired, anxious). My doc suggested upping it to 20mg but that just made me really anxious and have concentration problems. He relized that Lexapro wasn't working well for me so he switched me to Welbutrin which worked really well for me. My suggestion is try with the upped dose, if you don't like it you can always tell your doctor that and go back down, or you could discuss the options of switching to a different med, since it sounds like this one isn't working very well for you.

Good luck