Follicle size at baseline assessment

IVF at 39. What size were your follicles at baseline ultrasound (day 2 or 3 of my cycle)?

I was planning to start my first ivf cycle this month but my baseline shows a lead follicle at over 13mm in diameter and 6 others over 7mm (so 50% of my follicles already big).

I did an ultrasound last month (day 2 of my cycle) and I had no follicle over 10 mm and only one over 7mm. Why this difference ?