Undiagnosed but high BS after a big meal

So I’ve been a little concerned lately due to my bad diet and wanted to check my Blood Sugar. My girlfriend’s parents have diabetes and offered to check mine. I have checked it before, maybe a year and a half ago, and it was normal, granted I had tested it after not eating for a couple hours. Fast forward to last night, I was planning on checking it before me and her family went out to eat but we forgot until after we ate. I had a big meal. Big cheeseburger with fried mozzarella, fries, a few cokes, and a couple of bites of an appetizer. Now, my diet is bad but I don’t eat like this all the time. My soda consumption is bad but I rarely eat meals this big. Anyway, we eat, talk for a bit and when we get home it’s maybe a little over an hour later. They test my blood and it’s at 265, which really scares me. I know seeing a doctor is my best option but that might not happen for a few weeks. I’m really worried and I’m having a hard time functioning at work because of it. So, is 265 after that kind of meal abnormal? Could it be an isolated occurrence? I haven’t had increased urination or anything. I’m just really worried and could use some advice. I really appreciate it. I’m 26, if that matters. Diabetes also doesn’t run in my family but I know that doesn’t always mean you can’t get it.

Edit: not sure if it matters but we checked my blood pressure and it was normal.