First, you need to get together as a group, outside the session, and decide what game you're playing. Should combat be deadly? Should characters be optimized? You need to agree on that. It's possible to rotate between everyone's favorite activities to an extent, but only if the fundamentals are clear. It sounds like the other PC's, in particular, don't want to die, and that's okay. Remember, you're there to have fun, and it's not fun unless it's fun for everyone.
Next, assuming that combat is a major thing, and that you can agree on how challenging it should be generally, there are several ways to make that happen. You said your characters got hit regularly, but I don't see the problem if you survived and won. If it's that the other characters didn't get to participate, think about defensive formations that would let them attack without too much risk.
Also, it sounds like your GM is thinking head to head, but D20 combat is just as often about rock-paper-scissors. Sure your AC is high, but what about save vs. Enchantment? What if the monsters are immune to weapons? There are lots of ways to make a not-so-easy fight that don't require throwing juggernauts at you.
In the end, though, I think some or all of you will continue to be frustrated unless you can identify a single style of play that everyone's cool with.