slow speed crash 2 mo ago - side knee impact bump still

[SAMbike]

Just over 2 months ago I fell going very slowly trying to navigate through gravel in a parking lot on my bike. Although my tire was in gravel, my body hit pavement. The outside of my left knee took the brunt of the impact. It swelled up a bit and bled a bit, but I still went for a ride that day.

Since then it's improved a lot, and now, 2 months later, the only lingering symptoms are 1) slight soreness when I kneel on the outer edge of my knee cap, and 2) a bony lump. I'm trying to figure out why the lump is so large. It is very noticeable when my knee is bent.

I can push directly on the lump and there is no pain at all. It's not restricting my exercise and doesn't hurt in daily activities, so I feel silly going to a doctor about ... a painless lump. Through google searches, I think it is my "Gerdy's tubercle" ... but I still can't figure out why it's such a big lump 2 mo later. Any ideas? Photos:

Thank you!
-sam