Yeah, put the condom on first then put the lube on, otherwise theres more risk of the condom slipping off.
Also, make sure you get a water-based lube and not an oil-based one because oil breaks down latex.
I dont know how much you do, but you might wanna try more foreplay? I know sometimes its easy to skip that but it really does help with lubrication as well as relaxing you some more and preparing you (mentally, as well as physically) for having sex
You could even just try the foreplay, try experimenting, put a 'ban' on intercourse for a night so you each have to think up ways to please the other
You might even discover something new that helps
Maybe its something you could talk about with your bf?
I hope things get better Veronica!