Wow thanks again, this is very insightful and reassuring !
Thank you for your empathy too.
I can't really approach dev as a side project: I don't have a job anymore (luckily my lover agrees to share expenses and supports me but I don't want to be a burden hence hard-working on my game dev skills), and getting a "normal" job is not really possible for me. It impacts my health and my ability to do other things, so if I have a job I can't do game dev anymore. I'd just collapse every time I get back home - and probably be on medical vacation after 2 months. I'm autistic (with "probably a high potential but your IQ is irregular so it doesn't have a meaning to calculate it"), and being at a workplace every day, going there by bus/train (I can't drive I'd be dangerous due to detail-specific attention) is just too exhausting.
So I suppose my best shot would be to learn quickly and efficiently, maybe find other ways to get some income (like writing - I published a novel at a small editor in my early 20s, or learning arts and trying to sell some assets on Itch, or taking short job contracts (1-2 months) when we really need money), start selling small games with simple mechanics at a low price - even if I just get 30€, then 100€, etc... Maybe I should also see if there are small companies in my town or online that would hire me for short contracts or training.
I did study narrative structures 10 years ago but it was for literature, and I think it works differently in games because a good narrative must rely on a good gameplay that fits with the theme and story, right ? (I'm French so my English literary skills are limited too.) I also read that narrative games are not so difficult to implement but they don't sell a lot except for well-known devs/writers so I wouldn't rely solely on this aspect, I'd rather integrate strong narratives with another gameplay/game-style identity. I'm still fairly new and experimenting different mechanics so I haven't made any choices about this so far, I do need to experiment, improve my programming, game-design and learn basic visual arts skills. I actually think coming-up with a good plot won't be my main issue. (The one I made for this game was not very elaborate, I didn't want to focus on it too much).
Thank you again for your very kind support !