Not going as per planned

I took an extended holiday from work and was going to get into better shape, hit the gym on a regular basis, catch up on things, clear up all my outstanding chores, refine my forms, dieting and workouts, attend as many classes as possible, review my curriculum, but things aren't going as I'd hoped. I stepped on the scale and I've lost 14 lbs in 5 weeks,........this is not what I'd set out to do. For most people struggling with their weight this might be a blessing but for me I'm at the opposite end of the scale; "losing weight for me is a dangerous, slippery slope to be on". I understand the struggle with being overweight (whatever our advertisers/marketers or social media types say that to be), but I'm from the other end of the scale of always trying to stay away from being "underweight"; I eat until it hurts, I fill up before bed and wake up at 3am and have to have a snack, I'm 3 lbs from as I call it my "danger weight", where as soon as I hit 215 my weight can spiral down out of control and it stops where it stops and all I can do is sometimes say, "c'mon God, not fair"!!! The side effects of this are starting to appear, the loss of appetite, my fuse is a little shorter, refocusing takes a bit to notice, even though I don't seem to concerned; I can do 40 pushups in a row, I used to do 60, I can do 30 sit ups in a row; I used to do 50, I have a regular weight routine at the gym; I'm struggling with the endurance there as well, but on a positive note; the yard looks immaculate, the bikes and vehicles are washed and serviced, the house is ready for a "Better Homes and Gardens" inspection, but in all reality, if I'm caught up on all of this I'm usually doing too much. So, what to do? I guess this is one of those times where the adventure and learning begins when the plan changes and do what you have to do to get everything back on track.