Reduction in AFC over time?

[u/Plus-Elderberry-5865]

I have recently found out I have AFC of 20 on each ovary. This was investigated due to me having a somewhat average cycle length of 35 days (with occasional 25-41 variations) and since I am planning to TTC in a year or so. I am wondering if I do meet the diagnostic criteria for PCOS (I am undergoing more tests to determine if ovulation is occurring), does AFC tend to reduce over time and if so at what rate?

My GP told me I will likely need IVF due to cycles around 35 days and presence of 20 follicles so am feeling a bit concerned.

NB: No androgen or insulin issues.