I did a bit of Googling and found a good page giving some of the history of Waul's. It is the Bowen Family Page, see link below. According to this, Company C and Company F may both have been composed of men from Caldwell County and that area.
Lt. Oliver Steele of the Ninth (Nichols')--he enlisted the soldiers of Nichols' who joined the Second Texas Lancers-- became a colonel of Waul's.
In order to pin down the county in which a company was formed, I have found that you can extract all the names of the men in the company from the Civil war Soldiers and Sailors System Regimental list, then start looking up their names on the 1860 census.
The alternative is to hope someone else has already got it figured out correctly and has posted it on the internet. I can tell you from experience that the histories in the Confederate Research Center aren't necessarily correct, because one of them stated that Company B, 24th Cavalry was from Nueces County (Corpus Christi area) whereas it was in reality formed of Montgomery County men -- nearly 200 miles from Corpus.