I used the Aradalambion Index to Etymologies by English Glosses, and then double checked it in HoMe, V, The Lost Road, which is Tolkien's original list. You can get to this on-line list by clicking
here, then scroll down the page and click on Index to Etymologies by English glosses.... From there you click on index, and it will take you to the alphabet where you click on the letter you want for a particular English word. Once you know the Elvish stem you want, however, it's actually much easier to refer to HoMe.
The Index to Etymologies and LR shows the base stem that Tolkien used to develop the word; Lost Road also lists a number of the words that Tolkien later developed from that base stem. Like you, I am willing to "refine" a bit, sometimes using the stem and sometimes the later words, according to what I like best, especially since these are names. Names tend to incorporate archaic forms and stems as well as literal words.
The "gwae" that you cite, for example, is actually a variant of the one I used in both Wawaotok and Liwaiwa . The original stem for "blow" is "wa-, wawa-, waiwa". This same stem is used in Quenyan, Sindarin, and Ilkorin to form the word wind. "Gwaew" is the more common usage for wind in Sindarin; "waiwa" is used in Quenyan. In this case I preferred the Sindarin stem, which also happens to be a Quenyan word.
The same is true of your word "limb". This is actually a variant of my "Li". The stem for "many" in both Sindarin and Quenyan is "li". Later forms Tolkien listed include "li" (Q), "lin" (S) and "lim" (S) (actually blended with rim), usually at the end of words. I took the stem and used it at the beginning of the word.
Ot, Otos, Otok is similarly a stem for Sindarin and Quenyan for seven. Odog is a later Sindarin word. I didn't like the sound of "odog". I had visions of running in circles and barking!
(I believe your term "thul" actually means breath and is from the root "thu" that means puff or blow.)
If using the original stem is a problem, I will be happy to go back and look at the forms again and come up with something else, using only the later words.