I love coding, I hate my coding environment… Anyone else ever have this type of issue in programming?

Yeah, we all do, all the time. I swear the only reason therapists can earn so much is because of all the programmers are racing to afford them.

I would actually go talk to your manager about this. I feel you are unsure about whether the problem is:

• you always get the hardest tasks and thus seem incompetent among the others, or
• you actually can't finish tasks that others would be able to, they are just too nice to tell you.

If it's the first, then your manager should help ease the load, or at least you could get recognized for your efforts for doing the heavy lifting for the team. If it's the second, your manager will still be able to tell you that, and then at least you know you actually need to git gud.

all my tasks were opened years ago, remained open for months or years, then were assigned to me

That says to me, it's the first. I'd ask people when something like that gets assigned to me; what changed that makes it possible to close this that wasn't true in the past years? Or why don't we close it with a "won't fix", since nobody seems to have missed the thing for years?

That said, there are three things I'd like to say to that:

First, story points are not for you to obsess over on how many you can complete in a sprint. They are also not there to compare people to each other. They are solely to try to guesstimate how long something is going to take, so that the PM is not flying completely blind. If a task really was estimated at some points, then the team agrees you were justified in taking a lot longer, then the team fucked up with estimating. If that's consistent, then the team should have a conversation about why their estimates are off.

Second, yeah, the job market sucks now, that's also not on you. Try to obsess less about your work. I know it's really hard to do so, and I've gone through a bunch of experiences myself where I got closer and closer to burning out. Try to find something other than work to obsess over, that helped me a bit. I know it's hard. I've failed to do so many times already. If you are worried about your career, just know that every day you spend biding your time at the current place makes you worth more in a better market to come.

Lastly, it will get easier later on. I sucked a lot during my first few years. You learn through the suckitude. That's what you're there for. You will be able to solve these later in your career. These issues, not the code or the tricky bugs are the ones that need experience.