I just finished building my first DIY keyboard! Cheapino

This is the first time I built a keyboard!
A cheapino!
It took a little bit of time to get everything figured out, but I was able to finish that build relatively easily.
However, I am having trouble customizing the layout... I can't load it in the qmk.fm tool and when I upload a json file it gives me something that doesn't match my keyboard.
Also, the encoder currently types 'y' when turned right, I got 2 thumb keys working as spaces and I don't have a modifier key.
As far as I can tell, everything is soldered right, the diodes are in the right direction...
Did I mess up my soldering or is the cheapino firmware buggy?
Any app that can help me flash/customize my keyboard? I'll keep googling.
Thanks!