Thought I'd reply as I've had a similar issue. I had a colposcopy in May 2012 and my biopsy's came back with no abnormal cells whatsoever. I was told to have a follow up smear in 6 months which I did in December 2012. The follow up smear again came back abnormal and I had another colposcopy on 21st December. The doctor thought she could see severe changes so took further biopsy's.
I'm still waiting for my official results however as my doctor said they would be back in a week and I'd not heard anything, I called last Tuesday and was briefly told by the lady who answered the phone that my biopsy had come back as inflammation and the endocervical biopsy showed hormone related changes. I'm unsure at the moment what I need to do next but wanted to let you know about my experience. There are many different reasons our smears can show as abnormal. Good luck with your colposcopy and results, I know it's difficult but try not to worry - wish I could take my own advice at times!
Let us know how you get on :)