I'm a Leaf guy so if you have to go, so do I.
As for your weaknesses...
1) Chess.com does have "correspondence chess" - you can play one move every day / 2 days / 3 days / etc.
It would give you a chance to work on your end games without a ticking clock.
2) End games are a bitch. There is no way around it.
The number one phrase you hear at tournaments is...
...usually said by someone who just blew a winning position.
Look at what happened to Nepo in his 6th game with Magnus. He goes into the end game with a SLIGHT disadvantage. For hours Magnus tortures him and turns a SLIGHT advantage to a win - and Nepo is one of the best players in the world!
After that, Nepo was never the same and Magnus swept.
3) When to break thru is never easy. It doesn't have to be the center. Just concentrate on where your opponent is weak.
Or sac a piece and see where that goes. Again, if you are playing 10 minute chess, a sac can go a long way.