Tics only show up when I get nervous, mom doesn't believe me?

Have you talked to your psychologist about this? She might be able to help convince your mom that you should see a doctor. If not could you bring it up to your doctor at a routine appointment? If it is Tourettes it is possible to suppress tics, however they will come out eventually (whether it's in private or not). Anxiety can increase their frequency. I would really reccomend talking to a professional if you can, as regardless of whether or not it is Tourette's, it sounds like it's holding you back a bit.