Just relax, don't worry about it too much. Take a few days off, then try playing again if its getting frustrating. Don't get stuck doing the same things, try something new but not too complex. For example, start with two extended glutes then go from there. Or relax all, extend one glute and contract the other. Then go from there. It is pretty simple to create an attacking motion from those two. You can also easily defend a rush opener from there without taking too much damage.
For comebacks, just work on your positions. Don't go for a risky stuff a lot. I know nailing a risky comeback is pretty damn awesome, and it turns out pretty great if it has flow..but most of the times it doesn't work. Even great players, sometimes take the extra 50/100 frames to nail a good position. Lastly, if you can't finish your turn on time then don't worry about it...that'll work out with practice. And most importantly, ENJOY YOURSELF.. if you're not enjoying it.. then you're doing something wrong. :P