Osirisdon - Well, the first thing I need to advise you to do is please keep trying the helmet until you get used to it. None of us like to think about falling, but it is a very real posibility. And you might not think that a styrofoam bicycle helmet will help much, but it does. I'll spare you the details; but a few weeks back I took a tumble. Never saw it coming. I was whipped around 180 degrees and launched off my bicycle backwards. I landed on my tookus and rolled back and hit my head. There was no way of preventing it. It really rang my bell and I didn't get up for a few seconds. Had a hell of a headache for a day and a half. The back of the helmet was visibly crushed. If I hadn't been wearing it I would have been taking an ambulance ride for sure.
With that said; it sounds like you're in pretty good shape. Not many folks would be reporting a 16-17 mph average on their first ride. It will only get easier.
If you're stretching your budget to $600... perhaps you should check out this Bianchi
http://www.bianchiusa.com/06_castro_valley.html
and ride what you have until you either save another $200, or demonstrate whatever level of commitment your wife would need to see in order to somehow find the means to set you up with a righteous ride. I bet that if you really start riding full time she'd be jazzed to see you on something you really liked. I think that Castro Valley is sweet, all weather ride. And you'd probably haul ass on it. If I were in the market I'd consider it. It comes with 28mm wide tires. But it also runs cantilever brakes, so I'd bet you can fit at least 32's to help with those bumps. I can't for the life of me figure out why it doesn't come with a rack, but that's all it needs.
Just a thought. We'll keep lookin'. DanO