I really struggled choosing my monologues for drama school as I wasn't as knowledgable with plays as I probably should of been.
Theres no easy way round it... you could type 'monologues for teens online' but 9 times out of ten these won't be from published plays or are american or even if they are not I can bet a lot of people will be using the same modern monologue which isn't to great as theres so many modern plays out there!
Go to a library, go order lots of plays of amazon , you can get some for like £2. Type in on the search box Manchester plays, teenager pal, northern play, whatever! Read the plots and if there are characters in the play that seem to face a struggle you have faced, or are the same age/gender then just buy it and have a look through - it may have a monologue you really like in there.
Make sure your monologues suit you! This doesn't technically mean characteristics but age, gender ect.
I decided on Hang Lenny Pope by Chris O'Connell for my modern monologue and Benedicts speech in Much Ado About Nothing.
A lot of people worry that they may be doing a shakespeare speech that has been done lots before (me being one of those people) but i feel its best to choose a monologue that may of been done a 1000 times before if you feel comfortable with it as shakespeare can throw us youths out of our comfort zone. No Fear Shakespeare is a great website to look through shakespearian plays as it has the translation into modern day english at the side of the original text.
I would advise not to watch other people do the monologues you have chosen (E.G watching the film of 'Much ado About Nothing' or on youtube as this could effect the way you initially would have worked on the monologue and your creative mind may be a lot different to another actors interpritation.
Having said that below is the link of the Monologue I did, its bait rough round the edges as I just randomly did it whilst in bed haha but i thought id give you a taste of the type of modern I went for in order to contrast my Shakespeare monologue.
Peace!
