What size of round brush are you using now? For your length of hair I would think you would want a medium or large brush, depending on how much you want the ends to flip out or under. You can also try using a paddle brush to flatten it a little more. (Of course if your hair is as stubborn as mine, a flat iron is the only way to get it really straight! lol)
I know it will take time to grow out bangs, but why can't you back to the salon (or go to another one if you're scared of this one!) to have the layers adjusted? If you think layers are too thick at the ends, just ask them to add some more layers in ....
Also, you can always use a flat iron a few days a week or on days that it's really important to you to have nice hair, then try to use the blowdryer the rest of the time. If your hair's not too oily, you can flat iron it one day and not wash it and wear it straight again the next day. If your hair's just a little oily, try putting some baby powder in it the second day to sop up the oil! Right now, I flat iron my hair probably 3-4 days a week, and wear it in a ponytail the other days (since my hair's too oily to wear down the second day). I've been doing this for several months and my hair seems as healthy as it was before -- just make sure you use a good heat-protectant product! (I like L'Oreal Hot Straight, since it also acts as an anti-frizz/anti-static product!)
Of course, even though I'm also very self-conscious about my hair, I usually don't freak out that much at a bad haircut since I know it will grow out eventually! I went in for a haircut 7 months before my wedding and the gal cut it way shorter than I asked -- but it turned out okay, I just trimmed it once during the next 7 months (fortunately my hair doesn't get many split ends!) and by the wedding it actually ended up being the perfect length for the hairstyle I wanted! So you never know, after a little practice styling it or a little growing out, it may end up being a good style for you!