Hair Help!?

Every few months I get this nagging voice every time I look in the mirror. I have this issue where I can't keep the same hair color for longer than a few months.

Today was my birthday, and being sick I went for a low-key brunch with my girlfriends then spent the rest of the day considering different options.

I've been blonde:

I've been strawberry:

I've been brunette:
I think what I'm going for next is dark red:


I have to keep in mind that summer is coming up, and my sisters wedding (where we will be wearing pink) is this summer as well...

Help?