I have a decent background with c# and python, but am fairly new to GML, although I have owned GM v7, 8, studio1.4 but never spent much time with it. Now with studio2, it seems to be in a pretty good place and I am investing more time with it. But it is taking a little while to learn GML (2D stuff) I have even touched the 3D side of it. There are a lot of little nuances, as you continue to play with it you will learn more. My best advice is to start with a simple game like a break-out clone. Start small with a paddle/ball/blocks. Get the basic collisions and bouncing of the ball worked out. Then add things like score, and lives etc. You can add in bonus items that give you power ups like, triple ball play, or an expanded paddle length. Once you get all that down, you may want to look at adding additional levels, or even start playing with the room physics.
Bottom line, like any learned skill, you need to start small and build up from there. Just commit a few hours a week and you will surely build up your confidence in coding. And once you master one thing, move on to the next, perhaps an invaders style game, its similar to a breakout game, but now you would add in firing bullets, moving enemies, maybe shields to protect the players cannon etc. After that maybe a platform game.. just keep using what you've learned and keep on learning more and more. it takes a while but it is possible. Just stick with it.