Started my 7th Invisalign tray and it’s not feeling tight. Advice?

I’m halfway through my invisalign treatment and before I changed to my 7th tray, my 6th tray fit perfectly. Once I moved to the 7th one, it felt lose and not form fitting like my other previous trays. I can notice that on some teeth there are spaces. This makes my teeth not touch the bottom of the invisalign tray. Also, I have noticed that on my two front upper teeth that a gap has been forming. I’m not sure why this is happening but I’m worried.