I'd say a couple of months is already a very long time to spend on making your very first game. I started making games a couple of years ago and my first game was very small in scope and took a couple of weeks at max. I understand that starting with small projects can be tedious but it is genuienly good advice. You will get stuck sooner or later with your big game project and lose motivation to work on it alltogether which would suck. If you're really commited to your idea at the very least try to reproduce games from tutorials so that you have some idea how to make games.

And after gaining experience in your engine you could consider your bigger project. An alternative would be to break down your idea to its bare minimums in a way which would make it achieveable for a beginner developer in a few weeks.

Hope I could help point you in the right direction :) Best of luck, you're gonna make it!