Highlights gone wrong and how to fix?

I have dark blonde and highlights in my hair but the roots have grown in about 2 inches plus gray hair. I got the genius idea to try and do some highlights myself so I went to Sally Beauty Supply and got BW2 bleach and 30 developer. Turns out I'm not very good and weaving and sectioning my hair. It seems like now I just have 5 different shades of blonde throughout my hair and I'm just not happy with it. Any suggestions on what to do next? I was thinking about bleaching it all. I worry about the time it takes to apply the bleach with the time you should wait for it to finish. The beginning of the applications will end up sitting on your head longer than the last part of the application. So I'm not sure how all that works. Another idea I had was to try to color my hair with semi permanent color but I definitively don't want to turn it green.  Any suggestions on what to do next?