ready or not?

I'm at the point in my training where I'm starting to worry that I haven't done enough, but it's too late to do anything about it. On Saturday I did a 2.5 hour run. I was at home, on Southport, which is much hillier than where I run in MA during the week. I really don't think there is any stretch longer than 1/8 that is flat. I barely made the 2.5 hours. In the marathon I'd still have at least an hour and half to go. I know Providence won't be as hilly, but it might be hot, which scares me even more.
Sunday, I was feeling guility after eating massive amounts of Easter candy and treats, so I went out on my bike for about an hour and half. Again, in Maine there's no such thing as an easy ride because of the hills.
Subsequently, my legs have felt dead all week. Monday, I chugged through 5.5 miles; Tuesday I pretended to squat and lunge my way through kickboxing; and today I pushed out another 6 miles. Am I trying to do too much? I just really feel like I need to get in as much as possible this week, because starting Saturday I'll be in the desert of the Middle East. The heat, and a very busy work schedule, will severely limit my running. Then, I'm back and it's just a few days till the race. Clearly, I am not good at letting go and trusting that things will be okay.