Okay, so as we all know yesterday we were halfway through September. As I was logging my 18 miler I realized that I had already reached 99.6 miles for September.

August saw 131.1 miles

If I keep this up, September's mileage could be close to 180 

My concern is that it may be too big of a jump in mileage. This week I was hoping to get in a 20 mile LR while totalling the week out with 45 miles. And then next week would be a cutback week with a 13-16 mile LR totalling the week out with 40 miles.

Am I going to regret this?

I wouldn't worry about it - it's sort of "artificially" inflated with the MRT long runs, and it looks like you did the same thing I did with the long run for the week falling on Sept 1, which boosts things up too. As long as you're not feeling excessively beat up, just enjoy it!

 Lol I totally forgot my first 18 miler did fall onto September 1 and not on the last day of August (which LRB and onemile were trying to get me to do lol).

I'll just be sure to get some foam rolling and yoga stretches in tonight. It's too damn hot out and my training plan actually had today and tomorrow as RDs anyways. I also got to schedule an appointment with my massage therapist, go ahead and get in there either this week or next Monday.

It's not like this is your first year running or the first time you've run that type of mileage. That makes a big difference. Last year I went from 102 to 140 to 189 in consecutive months with no problems.

True, but my concern was since I haven't had high mileage like this since...... 2017? I almost feel like a newbie, thankfully though, I believe last year's and earlier this year's strength training has helped.

I'd just listen to your body, and do all the self-care things like you were talking about (foam rolling, massage therapist, etc.).

Definitely will do those, I would probably lose what's left of my sanity if I ended up injured and/or unable to run the IMM.