Brother has chicken pox - Have I had it? Should I still get vaccinated?

Anyone had any experience with this or have any advice?

I'm in my early-to-mid twenties, and I've never had chicken pox (I think). My brother is in his late teens and has just come down with it. Both of us were supposedly vaccinated some years ago, but apparently the time between the chicken pox vaccines is nowadays listed as about half the time we were told at first - obviously we're no longer immune.

His version has been extremely minor, as it was caught early and treated with strong anti-virals. He does have numerous blisters and is itching like a madman while he heals, but he hasn't had the bad fever or other severe symptoms often associated with the pox. Which brings to light the second part of this:

I've had two viruses in the last two weeks. The first seemed to be some sort of stomach flu, with nausea and a low-grade fever for about 48 hours. The second developed just last weekend, with stuffed up sinuses, runny nose, and a sore throat (perhaps a low-grade fever, but I couldn't tell). My sinuses are still not 100% today, and I'm still coughing. I've also had some acne-like breakouts on my face in the last couple months, but I associated them with my menstrual cycle. The one spot I had the longest actually looked more like shingles than normal zits or chicken pox... but it wasn't painful at all. None of them did that gross bubbling/blistering thing like chicken pox do, either.

So, my questions are... What are the chances of me coming down with the pox myself? What are the chances that I'm immune to it or have already had it without being aware? Should I still consider vaccinations in the future?