[mothered]

And I may have lost a lot of weight (like 20 pounds) that I needed, since I was already underweight...  

You mean you were already overweight.

Nope, right now I'm 5'9 and 109 pounds.

Anxiety?  Sounds right, I seem to have that and depression.  I'm getting that checked on soon (I hope) though.

Okay, I thought those who're already underweight don't need to lose any further weight.

Anxiety Is often linked with depression. Again, I'm not suggesting you have either, but more so generally speaking. There's many forms of depression and sometimes It can be difficult to find suitable meds. Do get yourself checked and If you're not happy with the diagnosis and/or prognosis, find a doctor who can definitively treat what you're currently experiencing.