60% + 30% + 20% = 110%??
Cutting I would suggest Protein intake at 1.2 to 1.5g per lb of body weight (satiation), fats at 0.3-0.5g per lb (hormones) and the balance from carbs.
I use IF all the time so I would be biased in favour of this, however as long as you are in a deficit you will lose...
I personally would not eat pre prepared mashed potato but in saying that you have lost on average over 1.5lb per week so you have been doing something right. Is this your typical daily food intake?
What is your daily caloric intake, are you tracking foods if not download an app such as MyFitnessPal and get a set of kitchen scales and religiously weigh and prep your own food, forget weight gainer shakes.
At 58kgs (128 lbs) I would suggest trying to add 0.5 to 1lb per week so would start...
Eating like a bird at 2100 kcals per day I would say highly unlikely it's fat, that would require an excess of 21,000 kcals and the 6 lbs you have put on in 31/32 days would suggest an excess of ~700 kcals per day if it was fat gain
I don't see a problem with training fasted then, I have trained both fasted AM and then fed PM and the only difference for me is a couple of reps less when training fasted AM so no major issue, however it may be different for others