no prob 
w/o retainer will be around 1 to 5 years, depending on the doctor,
your condition & also how fast your teeth adjust.
after your braces is took off, is better to wear retainer as long
as possible, there is one transparent retainer now, some doc is
still using those one line metal type. As there is not guarantee
that our teeth will remain straight forever..
actually i hestiate a long time b4 i decide to go for it, as its so
ugly to wear it. I dont even dare to open my mouth intially. haha..
but after a while, is like a used to it...
now u can choose the color of your braces.. i choose white, to make
it "less obvious"