Day 9 of ivf stimulation

I have 19 follicles in total out of which 13 were big ones . My doc said it's going great . But I've read a lot of posts says it's a bad number . Should I be worried about it? I've egg retrieval in 5 days . I'm 33 and husband is 37 . We are going for icsi pgt . My fish and amh level is normal . I never missed periods ever in life, normal luteal phase, ovulate every month. Why My follicle count is so low then ? And why My doc thinks it's great ?