I still don’t have a big picture view of what I’m doing or what I’m trying to achieve
If you don’t know what your goal is, nobody can help you achieve it. If your goal is to become a UI/UX Designer in the industry, people will judge you on your work first, you as an individual second, and your tooling last. That said, you will benefit from becoming competent with industry standard tooling.
Figma is currently the UI/UX design standard toolkit. 5 years from now, that may or may not continue to be true, though with things like Figma Slides, they’re digging their feet in (you might be shocked at just how much corporations rely on Powerpoint and Google Slides). Sketch will never “defeat” Figma with their current mentality; it’s simply not a goal of theirs. The only way that Sketch, apart from a significant change in direction from their leadership, will become the industry standard again is if Figma defeats themselves, which funny enough is always a possibility. Even when it seems impossible for you to win, never underestimate your opponents’ ability to lose.
I’m also wondering does sketch have a solid future?
Sketch hired a Head of Finance, Grace Fabry, in November. When a small company brings in a finance executive, change tends to be in the air. That said, Sketch has a few big corporate customers that I suspect are their lifelines, so if they can keep them happy, they should be stable. The irony of that is that Sketch has made it clear that their independence is part of their core foundation.
Speed, strength, execution, and a burning desire to overcome competition are critical business traits. But none of that matters if you can’t keep your books straight. The design world is full of idealists who prefer not to think about the bottom line.
I love Sketch; I’ve been actively rooting for them for about a decade. They’re still here, unlike InVision, who not long ago was on top of the software design world. Sketch will either get strong fast, or the market will leave them behind. Simple, hard truth. That said, I’ve closely monitored (and prior to their Adobe shenanigans, worked with) a few of the current Figma teams, and some of them are remarkably slow and have demonstrated a surprising amount of incompetence in getting core features out the door, despite their extraordinary access to talent and resources. I’m guessing this is partially related to server costs, since Figma is implicitly server-driven. But who knows – you have to sign an NDA to walk into the doors at Figma 
I will say that Sketch has been focusing on important work these last 18-ish months. But they were so slow for so long, that there’s just so much to be done to truly compete with Figma. About 6 years ago I wrote a long list of specific critical features that Figma was missing and issues the software had. I worked with some of their leadership to iron out some of those details at the time, but forfeit my support when the Adobe acquisition was announced. Since then, only a select few true missing features remain, two of which they are unlikely to ever pursue a resolution for.