Need job advice

6 months ago I got promoted to Payroll/ HR admin, mind you I have only worked at my dealer for a little over 2 years and worked my way up in the office starting from sales receptionist, so I have no prior experience. I feel like I am being taken advantage of pay wise as I am kind of used as a floater, meaning when someone calls out (contracts clerk, ap/ar, inventory), I cover their daily tasks for them on top of doing my own job tasks, also covering for my boss when she takes days off. I am only making $23/ hr (in California) for my current position. Prior to my promotion I was making $20/hr doing AP. When in AP I did ask for a raise and was told that it wasn’t a good time and that business was not doing good, all while raises were given to others. Now that I can see what everyone else is making, I 100% feel taken advantage of and am bothered that the GM and my boss will praise me to my face but when asked for a raise am not given it. Should I hold off and ask for a raise when I hit 1 year of my current position or do you think I need to start looking for other options that will compensate me better. I am actually starting to feel dissatisfied with my job due to the pay vs workload. Are my expectations too high since I have no prior experience?