Did colorfix, recolored, now what?

In my experience, after one colorfixes to orange or yellow, its best to use one shade darker than you want to end up with if you're going for the dark blonde/light brown range, because it tends to come out lighter.  (Not true if you were going dark brown, then you would use a few shades lighter because it would be too likely to come out black.  Color is a tricky business.).

Since you only want to add pigment, I would only use 10 volume developer, 20 is more lightening and more damaging than you need at this point.

I don't know what shade your hair is exactly right now, and I'm not familiar with the shade you used, I assume its a level 5 with a green base from that title, but I could be wrong.  You may not want to use a green base if you've already countered all the orange in your hair, or it may come out greeny (especially the parts that were yellow before).  If you just want to go darker, and your hair is a nice shade (not too ash, not too orange), maybe a neutral base would be your best bet.  At this point, I'd probably just choose the shade you want, or only 1 shade darker, don't go too dark since you've already darkened it some.  Otherwise, if your hair is still orangy or some other shade that's not what you want, you need to counter whatever color it is with the base of what you put on using the color wheel. 

Whatever you do, TEST STRAND.  I can't see it, so I certainly can't tell you what's going to happen.  Test stranding is the best way to avoid any problems.

Thank goodness!!  It came out lovely.