Not singing is a big down side to an act & venues like you describe thats fine for restaurant gigs but in front of a captive audience you gotta be an ENTERTAINER.......
I would video tape your act in full ....then watch it over and over as to how you can improve it.....then have your friends and strangers alike watch it and tell you what they think and how you can improve it.....then ultimatly get a singer which will cut your pay in half Argg! OR learn how to sing very well....competition is very stiff out there....as an analogy....You go to a good Restaurant, the food is good? You go home and tell your friends to go there to eat because it was good!!! Same in the entertainment business......

Good Luck