i was going to agree with the other posters that you need to increase your calories, especially considering how much you work out... however, you know your body far better than we ever will. if you've tried increasing food intake and don't like how your body reacts, then that's your answer.

i will say this... what our mind thinks we should see on the scale and what our body thinks is an appropriate weight to function correctly are all too often two completely different things, and no amount of argument from one is going to convince the other to change. that being said, we're talking about a difference of 2 pounds here. i'm 2" shorter than you, even though i'm about 80lbs heavier, and i honestly can't tell the difference between 200 and 198.

i know how it feels to have your self-image wrapped up in a number on a scale. my digital scale recently went schizophrenic on me and had me dropping 20lbs in 3 weeks. i won't tell you how absolutely ecstatic i felt... though the longer it went on, the more i realized there was no way in hell my body was really dropping that much weight. i got a new scale, and whaddyaknow, instead of losing 20lbs, i'd lost 2. i felt like i'd just gained back every ounce i've lost since last year.

the one thing i have found is that the more you obsess over your weight, the more likely your body is to do exactly what you don't want it to. if you can stop stressing a bit (because look at this logically, we're talking about 2 pounds here that could EASILY be water weight), you might find that as you relax, your body responds by going down.

you're already almost underweight. don't force your body into doing something that's not good for it.