I find I got only get a close shave if I go against the grain, which causes a rash etc.
I don't know if to just settle how it is, or go half across the grain? My razor bumps last a week+ so I don't want to try it and go down that route again!
I never go ATG (upwards for me) on my tache area. Not even XTG very often. Downward strokes are easiest and give me a decent shave. I will go over the area a couple of times though. If you are getting a rash just leave it and perhaps try again at this a few days later. I think even the cleanest shaved blokes probably have a bit of shadow visible on their tache area.
For the 'tache, try angling your razor (off vertical) strokes by about 30-45 degrees either way.
If you ever see the old Gillette Superspeed instructions, it recommends a diagonal stroke rather than a straight down on the chops. You're sort of imitating the cutting action of a slant.
I used to go ATG with a Mach 3 to get a super smooth finish. More often than not, it was a red and sore neck. After three whole weeks of DE shaving, I can get my BBS on tash and chin areas by 1 xWTG, and 2 x XTG [slantish]. I think you will quickly find your beard adjusts to a kinder way of shaving, and you will get a very good finish without ATG. Of course, YMMV, but that's what happened in my case. I did actually go ATG for a party at the weekend - and really wished I hadn't The improvement was negligible, but the effort and irritation required for the BBS holy grail wasn't worth it. As far as I am concerned, my DFS actually now = BBS
try shaving in the shower with a fresh blade and heavy handle..I dont get irritation anymore thanx to it..moisture a plenty n makes my lather very slick