Well, being told "everything looked in order" doesn't give you any useful information, it justs encourages you to buy fish at that store right then and there.
I'm glad to hear you have ordered a test kit. It's a very good idea to wait until you get it and test your water before you go back to the LFS to buy more fish. I'd recommend doing tests for a few days to get a good picture of what's going on in your tank, and make absolutely sure that you're fully cycled. If you aren't, then hold off on any more fish until the cycle is complete.
And I'm still wondering if you still have that pleco in there? If so, then that will definitely impact the number of fish you can add.