Identifying Manila Paper And Color Question

It looks like I have one wrapper.
Please kindly advise - is the DESIGN U93?
Would anyone suggest - whats the exact Scott U- number?
As an identification guidance I use this website:
http://dubinweb.com/envelopes.html
but still cannot identify correctly.
Please help!

Even though the first image is of a collage of envelopes, I assume we are interested in the pre-printed return envelope addressed to Dr. Eliot?

I am of the opinion the envelope is of Scott design U93, die 1, on white war paper. It appears (observing the top flap shape) to be a high-back U429. We can get a complete UPSS # if you provide a scan of the back and tell us the watermark number. Right now we have a UPSS # of 2230-??.

That war paper will drive you crazy.

Thank you.
Just a minute, I will make a few more scans.

I found the watermark, will upload the pic from the phone.

The circular die series was in use from watermark 19 (1915 contract) until watermark 43 (1949 contract). However, I believe only the three 1915 watermarks need be considered for your envelope, as "war paper" seems to be gone by the 1919 watermarks (counter examples will now hit my inbox bulk rate). With that large size envelope, there should be other examples of the watermark, but the one you provided looks like the top right (W20).

Thank you!
I will try to make more pictures.
Actually, I have hundreds of covers..many have different watermarks. Totally overwhelmed organizing them. Would you please share your knowledge - which Watermark is the rarest or lack of the watermark makes the cover unique?

a few more pictures; this cover is without watermarks.
6.3/3.5 inches

and this one is with Watermark 1919