The suspicion isn't the starter, it is the alternator and charging system. Where it runs fine if you jump it, that is a sign that the alternator is producing enough juice to run the car, which suggests enough to charge the battery. The 14v reading when running further suggests your alternator is working properly.

But even with this indicia that the alternator is fine, the fact that your battery is new-ish is a big red flag that you may have a non-battery problem. You see this often. Car won't start, replace battery. Car starts fine with new battery, for a little while. Then the underlying problem manifests itself, and it seems like you have a bad battery again. November to June might be more than "a little while."

My advice, take the battery into Checkers/Autozone/O'Reilly's/Part Zone/NAPA/Pep Boys/Wherever and have it tested. They can test it in the car, and give a basic test to the charging system, too. I prefer to take the battery out of the car and have them test it, though. Testing the battery is the only way to confirm/eliminate the battery as the problem. And given the 2-battery history in less than a year, I would want to confirm/eliminate the battery before buying a new one. Testing is free!

Also, as obvious as it sounds, poor connections at the battery are surprisingly often the cause of starting and charging problems. It is well worth your time to clean your terminals, tighten clamps and connections, etc. as part of your diagnosis. I have a 2000 Hyundai where the battery-terminal-connectors have stretched. I bought $1 shims from Autozone and it fixed a long-standing starting/charging issue. They were just hanging by the battery display.

Those are my thoughts, FWIW.