Welcome. Gee, it sure seems likely that your problem is your oven. Get yourself an oven thermometer so you can manually adjust the temp.
In the meantime, why don’t you call the manufacturer and also the place where you purchased the oven to see if they they will offer you an extended warranty - then have the repairs done. That’s what we did when my husband broke the interior door glass on my KitchenAid oven - the oven was 3 years old and the warranty cost less than the price of the replacement glass not including the labor. Oh, another idea is to call your local utility company to see if they offer a service/repair plan of some sort for major appliances - there’s a gas company in MN that covers the service on many major appliances for just a few dollars a month.