Imposter syndrome for first ultra

So I’m not a smart man and signed up for a 100 for my first ultra. I’ve been running for about 15 years but never raced anything longer than a 10k until about a year ago. Since I committed I’ve ran several half marathons, a full marathon, a full trail marathon and have my first 50k next weekend. This year I average 7 runs, about 8 hrs, and 50 miles a week. The 100 is in two and a half months and I am ramping up miles until the taper at 3 weeks out. I’ve been training nutrition and really dialing in my plan. But I have days that I still feel like I’m not doing enough. Am I prepared enough or am I setting myself up for failure? Sorry if this is a dumb post I just don’t know where to seek advice.