Saddle Sores - Sorry maybe TMI

[KnottedYet]

Ok, measurements. Inner edge sit bones - 3 inches
Outer edge sit bones - 6.25 inches.

Do these measurements tell me anything?

No pic as yet. That requires cooperation from DH. I might be able to get one tomorrow.

Cool!

Ok, first I convert to metric, cuz that's just the way my brain works. 6 1/4 inches is near enough to 16.5 cm to make my brain happy.

Saddle width: take your outside measurement and add a centimeter or two to either side to give you a saddle width that will completely support your sitbones (lifting you off your soft tissue) and give you wiggle room to shift as you change position and effort.

16.5 cm plus 2 cm (1 cm each side) is 18.5 cm
16.5 cm plus 4 cm (2 cm for each side) is 20.5 cm

That gives you a saddle width range of 185mm-205mm or 7 1/4 inches to 8 inches.

Saddle top contour and profile: T or Pear, curved or flat, narrow nose or wide nose, I don't know any shortcuts to figure out what works best. It seems to come down to trying a saddle, making note of the shape and contour, assessing comfort, trying another saddle, etc. There are pretty distinct chafing patterns for mis-fits. (like a saddle that is too pear-shaped will chafe in the "panty-line" of your buttock)

Cut-Out: I found this groovy cut-out home test, and don't remember where. So, my apologies to the universe for my plagiarism. Sit in perfect posture on the forward half of a hard wooden chair clad only in your underwear. Keeping your back straight, hinge forward from your hip joints until you can rest your elbows on your knees. If your soft tissues in this position are getting smooshed against the chair seat, you need a cut-out. If it feels like you could sit this way for a while, you might need a saddle wide enough to support your sit bones completely (like the chair is) or a saddle with less padding to bulge upward and crush into your tissues (like the plain wooden chair has no padding).

Edit to add: I went back and looked at the link you gave to the saddle you have now. 138mm (5 1/2 inches) doesn't really match up well.
(When you find a saddle that fits buy a couple. Your bones are what matter, and they'll stay pretty constant... unlike the saddle styles! Seems like as soon as anyone finds the perfect saddle, that one goes out of production!) Oh, and hip width rarely has a hot correlation with sitbone width for women. Tiny women can have wide pelvic outlets and vice versa. Nobody can really look at a woman and determine what width saddle she needs, they gotta get all intimate and measure those critters one way or another!