Sounds like when I built mine. I wore a sweatshirt most of the time working out there and the floor had a slight slope and mine was just a little out of square, dad added it on so I know it would be close.
The slab looked like it was poured about 6 different times. In a 20 year span. Some of it looked like bag mix pours.
I couldn't take it anymore yesterday and put a heater out there and worked for a few hours. Framed the entry room and closet in the kids room. Tonight I am going to start framing the master bed room. After its complete all my framing is done and all that's left is wiring insulation then drywall! Once the ceiling is hung I am golden for work. I love finishing drywall and it goes quick.