Stop telling yourself you need to get better, you're putting too much pressure on yourself to ever improve or be happy.
If you focus on where you aren't, it's too intimidating, and won't ever motivate you to improve.
Instead, accept that where you are is okay, you're only 24, you have a LOOOOONG lifetime to figure this shit out. Just don't make any truely fucked up decisions, that you won't be able to come back from (ie. don't stop going to work, whatever else fits here)
Loneliness is aweful, which is why it's essential to talk to people. If you don't have friends, start playing some kind of mmo, (don't let it fuck up your life) you can make "intro" friends there.
If you're not sure how to change, here's my summary (may be incomplete)
I'd say the easiest / most important thing to improve is diet and exercise, if you're not sure where to start. Getting diet and exercise in control gives you more self confidence, which starts a snowball effect in the (other direction) of depression. Just don't develop body dysmorphia.
TL;DR: Get comfortable in the situation you're in, there's no reason you NEED to do better. Only try to change if you know you WANT to.
Armchair expert, so fuck my opinion.