Dual Jobs: When an employee is employed by one employer in both a tipped and a non-tipped occupation, such as an employee employed both as a maintenance person and a waitperson, the tip credit is available only for the hours spent by the employee in the tipped occupation. The FLSA permits an employer to take the tip credit for some time that the tipped employee spends in duties related to the tipped occupation, even though such duties are not by themselves directed toward producing tips. For example, a waitperson who spends some time cleaning and setting tables, making coffee, and occasionally washing dishes or glasses is considered to be engaged in a tipped occupation even though these duties are not tip producing. However, where a tipped employee spends a substantial amount of time (in excess of 20 percent in the workweek) performing related duties, no tip credit may be taken for the time spent in such duties. .

So the question becomes if OP spends an excess of 20% of time doing wait staff duties.