depending on how many days you train, drop the pointless repeat mode and try and target each muscle group per workout or hit each muscle group hard at leasy every 7 days.
Start adding some big basic compounds in there aswell: squats, leg presses, incline/decline bench, pullups/chins, lat pulldowns, deadlifts, upright rows etc. Think you get what im saying.
Being as the legs for most people are only hit once per week, hit them the hardest
I know how you feel as i now weigh only a 142lbs due to having celiacs disease for a long time without knowing so im more or less now stuck in the same boat as you as far as the weight goes.