I too was in the same position as you. I was having smears since I had my first baby I'm 26.
All my smears have been normal but in Feb I got the same result as you.
I went for Colposcopy in March, which in my opinion is a painless procedure, similar to a smear test but longer.
There is a bit of discomfort from them staining cells and stuff but nothining too sinister.
I had a punch biospy taken on the same day and after two weeks I got results that I had CIN 3.
In your position, I would go for your Colposcopy as planned and ask as many questions as you like this will reassure you.
If you have to get a biospy taken dont panic, its just to see what the cell changes that are present on your cervix are.
It doesnt mean you have cancer, but if the cells need treatment you should have peace of mind that you will get the treatment required.
Hope something I have said helps.
Best Wishes xx