I am 5 weeks in with full uppers and lowers. I can not seem to find a product that will keep my lowers in for more than a couple hours. That's without eating or drinking. I have had one soft reline and will be having a hard reline April 20 but I am going insane with this loose denture!
I have full dentures for about the same length of time as yours. I would contact your dentist and see if they can reline your lower denture. Unfortunately, I have the same issues as you. I have been using the Fixodent with Scope and that doesn't last as long as the other ones. The "free" Fixodent seems to hold way better than the other ones. Plus, you might need more adhesive. I am considering an implant for my lowers since the lowers are considered floaters (no suction like the top).