GFI switch and outlet

Ok I have a issue that I need help with.
I’m not a electrician and thought I could handle this.
Bathroom has a single outlet with a built in switch all works. I mtrying to replace with a new but same thing but gfi, outlet on bottom switch on top. Wires in the wall, 2 bundles of wires each bundle has a black, white, ground wires. New switch has 4 screws bottom 2 are line, top 2 are load, and then 2 black wires built in to the switch.
Here’s the issues both bundles of wires in the wall have 120,tested with meter. I guessed a few times on what goes where and nothing works switch or outlet but I did get a green light on the outlet to come on.
Any help?
Thanks