Why/How are my eyes changing colours?

Ok….So when I was young my eyes were really light sky blue, Then Dark blue circles surrounded the Iris, Then they got a darker blue, A few months later the Iris…..fragmented? (From smooth blue to little sections…) And when they did that a brown spot appeared in the Iris of each eye…..

Since then the brown has spread from one little spot to most of the inner Iris around the pupil…..And is still slowly spreading.

I have really good eyesight checked regularly I’ve spoken with the doctor about this and he didn’t know…but offered to send me to a specialist I declined As this doesn’t really affect me….except for my curiosity…. lol…A lot of people think I have green eyes…

Any ideas?