Read and "learn cold" two books --
1) Paul Littlewood, Chess Tactics.
2) Jeremy Silman, Essential Chess Endings Explained Move by Move.
Both books are relatively short., and involve well defined, bite-sized tactics and strategies. You can't play decent chess (ever), without learning this relatively small "body of knowledge."
The knowledge you acquire therein, will surely (and eventually) catapult you above 1200 Blitz on this site. If not, maybe you need to try a different game than chess. Sorry.
Lastly, put a 5 second bonus into any time controls you play. That will allow you to reach the end of the game "on the board," instead of "on the clock."
Very Simple. Good Luck With It.
I sympathise with you. Started playing a year ago. Family, work etc limits me to about four hours a week also. But, happily I've now beaten my own nemesis once, which is encouraging (he's about 1300 otb rated). Did notice a big jump in understanding after playing through lots of exercises. But I still play erratically: from very solid and patient to lazily and poorly. So, I'm not one to give you tips methinks...