Welcome Stephanie!
The times people have asked Dom whether a particular character was based off of someone in his real life, Dom would usually answer that whilst someone may had had characteristics of people he knew, no character was really based off of anyone in particular.
There were times people asked if Dom had issues with his parents because all his story parents were mean (Dom's folks were not mean). And some asked if Dom were a twin because there seemed to be lot's of twins in his stories (Dom's not a twin). I think the closest we got was that Taylor from TOU have several characteristics of one of Dom's one time BFs.
So anywho, it appears that all of Dom's characters are figments of his creative imagination .
While you wait patiently (or impatiently) for ITFB 21, I'd suggest re-reading TOU, TLW, & DD. There is a tremendous amount of detail that you might discover if you had previously read each store in one shot.
Welcome again, and hopefully Dom will be off hiatus soon* !
Take Care®,
Vic