However from absorption of advice from here, various subreddits and Discords, YouTube channels, Actual Plays and of course, the best teacher ever in direct experience, my confidence is starting to grow. Which is saying something because I am traditionally NOT confident even in things I'm proficient in (e.g. career).
Recently I ran the Alien RPG one shot, and all players involved told me on the strength of my session they were going to buy the system. I've got a lineup of about 15 people at my FLGS waiting to try that system and get in my other game (Numenera) and have been mindful of actually accepting a lot of positive feedback from that game. I've even been offered a business opportunity in being an NDIS service provider alongside someone else to teach living and social skills through TTRPGs to at-risk groups and communities. I have a couple of families already lined up wanting to start.
But I honestly think one of the greatest resources I've had for, well, resources, advice, opinions on new systems, motivation to try new systems, confidence building etc has been right here on this subreddit. So thanks, r/rpg, you've really helped turn the page (pun intended) on my confidence as a GM from a total wreck to a teetering but slightly more confident almost-wreck!