ttc #2, but uderweight?

Hey y'all. My husband and I have a beautiful little girl who will be turning 2 this Saturday. We started ttc #2 last month and I have been off bc for 2 months. I have epilepsy and take keppra xr 1500 mg daily, as well as prenatal vitamins, and 4 mg of folic acid just in case (even though keppra hasn't been found to cause any birth defects some anti epileptic medications can, and folic acid helps minimize risk). However, since I started having seizures my anxiety just went through the roof and I lost so much weight. I have always been small but at my most fit I weighed 125, and I weighed that when I got pregnant with DD, and I continued to lift and workout and had a great pregnancy. Well, a few months after I had her I had my first seizure (I have simple partials so I sometimes act odd or shake on one side or zone out but I don't EVER black out.) My seizures have finally greatly diminished. For a while I was having them several times throughout the day, now I'll only have a mild one about once a week. I'll just feel odd for a few seconds and then the feeling goes away. So I'm doing so much better now. However, I haven't been able to gain all the weight back. I do yoga daily to help stay calm and I see a therapist as well. (I am a naturally high strung person so the epilepsy diagnosis really got to me.) I weigh 106 now and I struggle to eat enough (the anxiety and my meds killed my desire to eat) but I DO eat, and I do strive to take care of myself. Also, I am 5 foot 4 inches. My husband and I want another child so badly, and we want our DD to be around 3 when she gets her little sibling. I guess I'm just looking for some encouragement. Do I weigh enough to conceive? I've already spoken to a high risk pregnancy doctor about my medication so I'm not worried about that. And I still have my period and it's very regular. I'm just scared I'm underweight, but no mater what I do I can't seem to weigh more than 110. (My weight fluctuates between 105 and 110.) Any info, tips, encouragement is greatly appreciated!