Abnormal smear & colposcopy

Hi ive never used forums before but thought I'd give it a go to hopefully set my mind at rest.

I had my first smear in january which came back as low grade with HPV to which I freaked out and had a private colposcopy done. When i had the colposcopy done he agreed that it was low grade and said to have another smear 6 months that.

I had one done 4 months later as was too impatient to wait and then the results came back as high grade to which the doctor said it was moderate changes. I had a colposcopy done 1 week after the results and 2 biopsies taken to which I'm waiting for the results.

My question is how could it have changed from low to high so suddenly and if they got it wrong back then what says that they haven't got it wrong this time and how likely is it to come back as severe rather than moderate or maybe even worse? I feel like I'm loosing my mind waiting for results (which has only been 11 days so far) and I feel like I'm loosing faith in doctors which worries me. 

If anyone could help I'd be so greatful.

Sarah xx