u/megajo5

I just wanted to gain some perspective and see if this was normal. I began my treatment in January, and I was instructed to wear my first tray for four weeks, which felt excessive. I am now on tray 9 and have had two week changes since the first tray. I honestly haven't noticed much of a difference in my teeth at all, and it's been 5 months. I assumed I would eventually switch to weekly changes, but I just looked on my Invisalign app calendar and every tray until the end of my treatment which is a year from now is a two week change. Is this normal ? I pay my orthodontist monthly, so I am paranoid I'm getting scammed.