Sounds like you alredy know that getting enough calories is the first thing you should worry about since BP is in the normal range, albeit low normal. Cutting back on caffeine may help to increase appetite.

How many calories are you eating per day? Are you using fitday.com? You "should" (I hate saying should!) be eating at least 10 - 12 times your weight.
ANy idea how close you're coming to this goal?

JInx