[drawkbox]

Most developers need 5-10 years to really get to be engineers and solid product makers. Until then work on teams that are better than you and get as much experience as possible.

Keep doing what you were doing in .NET or something you can take on. Maybe explore some new areas/platforms but only when you have some projects in them. You can learn to deliver product on any platform but change it up when you have the ability or in your free time. Start small in deliverable chunks always and build from there.

I feel that you need to slow down, write sentences into paragraphs, figure out what you want. Be concise.

You are focusing on the 30 year old thing, most developers are their best in their 30s+, so don't believe the hype. Think about it, graduate at 22 or 25/6 with masters if taking that route, 5-10 years of experience puts the best of their industry right at early to mid thirties as the starting point for good developers. Just because VCs want developers before you know your value doesn't mean good developers aren't needed. You need to focus on making yourself better in your eyes. You aren't there yet but you are on the journey and you are thinking about these things so that is a good sign.

Keep working at it, you have time. Right now though since you feel a little lost, just take on a .NET role, or something you can take on, and rebuild your confidence. You can make a product on any platform and you will learn many good patterns and anti-patterns even if that is not the platform you choose in your own projects. What you need right now is experience and some of it may suck but find the good/fun/learning in each adventure.