Firstly, 118 lbs is too freaking small, 5'3" or not. that's a 6 foot guy weighing between roughly 140-150 lbs. Shit, 6 foot basketball players weigh at least 165 lbs at the competitive level and they're still skinny (as well as being very short to play college ball). You need to add at least 20 lbs on your frame to look "normal", and about 40 lbs on your frame to look like you train with weights.
Secondly, This training split is not something conducive to back and leg strength which you admit is your weaknesses. The greatest problem with people not seeing results is their refusal to concentrate on their weaknesses because they don't like it, or are ignorant of how to do it, or are just too damned lazy.
So, your new split is this
Day 1--back and legs
Day 2--chest and shoulders.
Day 3--back and legs
Day 4--chest and shoulders
Workout 4 days a week and pick different exercises for each day. at 118 lbs there is zero need to focus on biceps. None.
Include good mornings on 1 of your leg days, and deadlifts on the other. Also include rack pulls on one of your leg days. Make certain you do the exercises with proper form--especially good mornings. Good mornings are the best lower back builders there are but you need to do them properly at all cost. Don't ever go to failure on good mornings. That is only acceptable for experienced trainees. For you it is too likely to be dangerous in the foreseeable future.