Help! Stained Hair

My name's Emily and this is my hair story: I started dip dyeing my hair a few years ago, mostly pinks and blues using Smart Beauty products.  The dip lead to me dyeing the whole bottom layer of my hair the same colours, and eventually bleaching that layer to a very light blonde. My natural colour is darkish blonde.

I finally persuaded my mum to let my dye all my hair pastel colours, so of course I had to bleach all my hair. I've always done my hair myself with a little bit of help from my mum, but she only covers her grey hair and had no confidence in helping me bleach mine. After the first bleach my hair was two different bleach blondes, more yellowy on top and very bleach blonde on the underneath layers. I didn't want to bleach the top again so I just threw on a diluted Directions Carnation Pink which turned out a lovely pink on top with some purple tones underneath (due to the underneath layer being slightly blueish from a dip layer dye job) until it faded to the salmony orangeish pink! So I kept dyeing my hair all different colours.

My hair is currently a weird light blue, green, mint, seafoam colour with about 4 months of roots and I want rid! It seems to be stained from the use of Directions Lagoon Blue and Violet with several applications. Before I dyed it purple (again) I bleach bathed it all which only lifted the green colour to a more luminous green! So I made up a light pink toner with conditioner which seemed to work. Regrettably, after I'd reached an okayish bleach blonde I dyed it purple (again again), and I am now back to the green colour.

Any suggestions on how to get it back to blonde, or should I dye it brown, using a box red beforehand?

I can't afford to go to a hairdressers and have it done professionally. Should I do more bleach baths with some more pink toning? I've personally found that the baking powder/bicarbonate of soda didn't do much to my hair...

Sorry for my lengthy first post... All replies appreciated - prom soon! D:
Em xx