Attack of the Monster Follicle

All my worry about timing was for naught. Would you believe I still haven't ovulated? I have one monster follicle in there. But why is it still in there? Here's a recap:

CD11: no follicles, lining at 3mm
CD14: follicle at 13mm, lining at 5mm
CD17: follicle at 20x14x13mm,* lining at 8mm
CD18: follicle at 21x16x15mm, lining at 9mm
CD19: follicle at 21x18x20mm, lining at 10mm
CD21: follicle at 25x23x20mm, lining at 11mm

So here's my new worry (because I must always worry about something). Am I overcooking it? I feel like it was big enough to go two or three days ago.** I've never seen anything bigger than 21 via ultrasound before, so 25 seems huge to me! Will it be stale and overripe by the time it releases? I've read that quality of both follicle and lining deteriorate after CD21.

Anyway. I'm done with monitoring for this cycle. (Yesterday when I got home from OOT, just for fun, I POAOPK for the first time on one of the 50 Internet cheapies I bought and got an almost-positive. Exciting stuff!) I should finally ovulate today or tomorrow.

* All three measurements refer to one follicle. The u/s tech gives me three measurements for follicles over a certain size, so I get a 3D effect. On CD17, for example, I commented that my follicle was weirdly oblong, and I was assured that shape doesn't matter.

** EDIT in response to comments: I don't know why we didn't trigger. It was a natural cycle and I guess Dr. L figured it would happen in its own time. Interestingly, though, I looked back through my notes and was reminded that he wrote me a prescription for a trigger I didn't end up needing back in November when we discovered by chance that I was about to ovulate on my own, so he's not opposed to triggering on a natural cycle. I guess he just wasn't concerned. If this happens next cycle I will definitely suggest triggering.