If you can continue to grow your experiences in your current lab, get paid instead of going into debt or spending money on a Master's and try to get another poster or two in - RA job 100%.
I think Master's can help people switching careers but I know a lot of people in Master's who still don't get in after the 2 years and have more debt. Plus you are competing with a ton of people looking for the same opportunities in the Master's while in your current lab YOU get to be the lab manager. Stick with it or apply to other RA jobs! It is hard to get a full-time RA position so congratulations!!