Freaked out – keep getting told my results are actually worse than they thought

Hi everyone,
Would appreciate your advice/thoughts as a bit freaked out!
I had an irregular smear result, following which I had a colposcopy. The nurse (who I wasn't crazy about as she seemed pretty dismissive) said it looked like CIN1, but she did a biopsy just in case. I got the results letter through which said it was CIN2, and advised that a follow-up colposcopy appointment would be scheduled in 4-5 month's time. Luckily I googled this and saw that most CIN2 cases are treated, so I called and spoke to the nurse (who, to be fair, was nicer on the phone!) and she said that as it looked like CIN1 when she examined me she decided to wait and see if it improved before having LEETZ. However, she said it only had a 20% chance of improving on its own to CIN1, (50% chance of staying the same and 20% chance of becoming CIN3) so decided to book myself in for the procedure as I'm getting married in a few months and want everything out of the way beforehand. When I told her this she offered to get a senior pathologist to examine my slides, in case it was misdiagnosed as CIN1. Anyway...after all this called back the other day and was casually told "oh, you definitely need to have LEETZ as it's CIN3!) 
Now, I know that CIN3 isn't the end of the world, but as they keep on getting it wrong and raising the level (and initially didn't even want me to come back for 4-5 months!) am really worried they've got it wrong yet again, and it's actually more serious. Am trying to stay calm, but have just started spotting (a week before my period is due - and I'm on birth control) so am pretty freaked out. Any advice/thoughts?
Thanks x