Too much weight loss

I am type 2 and not overweight, on Metformin and simvastatin. I've dropped loads of weight which is fine except none of my jeans fit anymore, but I am in danger of losing too much. What the heck can I eat to prevent me turning into a skellybone?
I have cereal with fruit and skimmed milk for breakfast or eggs and bacon. Ham salad or sandwich for lunch and a pear or kiwi. Eggs chicken or fish and veg or salad for dinner and maybe some Greek yogurt and sugar free jelly.

Not deliberately active as in very little exercise other than busy walking around at work, I take a two hour walk on Saturday and Sunday and am quite restless until after dinner when I slob out on the the sofa. Not keen on fatty milk, it tastes like oil to me.