Your 18 with no back issues and you lowered the seat 1 inch since the picture?
the set up is all wrong, you are sitting way to upright on a saddle that isnt made for upright sitting. That stem needs to go, and go fast. and you need to smack the $25 fitter for letting you out of the bike shop without telling you this.
i will forgive you for having a white sheet over your chair because your 18 years old.