What could be the reason why my body seems to be tilted to the right?

I mostly notice this when Im riding no hands on straight ways. The bike runs straight but I absolutely feel that the bike under me is leaning left while my body is leaning right to achieve balance. Never had a bike fit so all adjustments are made by me.

Could this be a weak muscle?
Could be one of my legs is shorter than the other?

I mostly ride solo so i try to get some videos and that’s where I start to notice. My right leg seems to be more fatigued fast than the left too.