New to gaining weight, trying to kick this in the butt

Newbie...Trying to figure this calorie counting thing out. BMR TDEE ect. due to recent weight gain. My story. Age 18-24yr worked at restaurants ate all day whatever I wanted and worked out w/ weights 30min a days stayed around 112-115, I'm 5'4. Almost had six pack but still a tiny belly pooch. Worked for me. Moved to start college and try to make more money. Lived in travel trailer and lost gym membership. Weight dropped a little then stayed around 115-118. @26 got a contracted desk job 5/2. No more breakfast and lunch only periodically, dinner ate a good plate and a desert. (work is an hour from civilization to lazy to pack lunch). Weight still around 118 vacations would jump to 125. @28 got hired on as an employee so now had excess to the weight room, worked out for my half hour lunch added scoop of whey protein and had snacks available provided by work. Weight changed to 116-119. My squats from free-weights to 270lbs on a stationary bar. Last year @29 decided to leave guy I was with Aug-Sept dropped down to 106lbs by mid Nov. like it was nothing (stressed & back to being broke). Started talking to a new guy and putting weight back on. Did stop taking my protein shakes around same time (heard too much can cause weight gain) and dropped squats down to 90lb (didn't want to get hurt at work and ruin free gym for others). Didn't snack as much during the day (thought sitting on butt = should prol eat less) and drink a little more on weekends now then before. Hit 125 average and started googling, drinking more water and grabbing smaller plate for dinner.... then read about BMR and TDEE, breakfast start your day and all that. I calculated 1300-1500 BMR different sites and TDEE 1800-2000. Now eating fruit at work and nuts etc to try and at least get more calories before I leave work and drink a few bottles of water. Didn't realize that I didn't drink that much. Now hit 130lbs but seem to be staying under. Worried about this eating more thing but would guess I wasn't getting over 1000calories a day with just one meal on a side salad sized plate. Adding some jump rope and couple new ab exercises (maybe my muscle got bored of the same ol routine) to my 30 min, added back protein and increased squats to 160lbs....going to see if anything happens. Keeping figures cross, be happy with that 116-118 range again even though I could buy the tightest outfits at 106-110 Blood test show no thyroid issues or anything weird, think I just jacked my metabolism up