Good to see you're back on the forums. Much has changed since you were last online here. That is to say, so many maps have been uploaded, and VGMaps grew greatly.
I presume your PC's hardware's not capable of seeing and/or making larger maps because of how your present configuration is. Others have done some upkeep on it time to time. But, there's still loads of games out there yet to be mapped, and lots more to come.
To be on the safe side, and to keep what you have without disposing your work, programs, and so on, in my safe and wise perspective, I think you might need an additional PC, should you save enough for it, that is, with stronger hardware, more memory, etc., if you want to take on doing larger/longer maps for your work, while keeping and preserving your PC, and backup everything you have in your separate, external drives.
There's also, of course, specific programs that help streamline such processes, such as Tiled, not that you've heard of it before. It's a very good map editing program, once you get the hang of it.
Nice to hear that you're back on your mapping progress, though! Hope you can still keep it up.
I feel that, to be honest, long-absent mappers that weren't here in long should be a bit more communicative now and then, just to keep getting acquainted. We should try to communicate a bit more often.