Car does not start. Battery, starter o.a. defective?

Hello dear forum, I’ve already goneugled, but I didn’t find what I’m looking for, or maybe I didn’t understand 100%. That’s why I want to turn to you now. I’m driving a Honda Accord Type S from 2010. Now to the problem description… In September it started that I wanted to start the engine and it hit about 2 sec. until it started. Not top, but for me completely ok. Until December no changes and then the car is always swollen. even after the key turned around only a short sound came (starter turned), 2 sec nothing and then he jumped on. Often the car didn’t jump at all. When pushing on it he always jumped on without problems. After longer car rides >30 min with switched on heating, sitting heating and music he almost always jumps on without problems. After short drives without power eaters had to be pushed off and on. I always have this on the B after 1 day in which the car was not moved, I measured the voltage… 12,43V and the car does not start… what should I think of it? I ask for quick help, because I like to know what is missing my car. If I have not described something, then please ask again. Hope you can help me further. MfG. P4ss0