Sometimes I put a safety pin on the RS of my work, and keep moving it up in my field of vision as the knitting gets longer. The safety pin helps me be aware of which side I'm on, if it isn't o otherwise obvious. You can also tie a contrasting color of yarn to the right edge of the RS facing. Anything to help you stay oriented.
I've been knitting for a lonnnnnnnnnnng time, many years...and just last night I set my project down in the middle of a row, having to take care of something....then picked it up again 10 minutes later, and started knitting back the wrong way. Doh. Well, after the end of that half a row, the middle of the NEXT row was wierded out, like you described...and I realized what I had done. Good Gravy!
Try the safety pin thing. It helps especially with garter stitch, and other pattern stitches that look identical on both sides.