I've been developing a fantasy story but i'm just worried that there is way to much stuff going on and that it might be to hard to follow if i keep the ideas the way they are... any suggestions on how i'd know if i need to cut out things?
Write the story first, then worry about how confusing it might be. You might be able to tie it all together at the end. I write VERY long fantasy serials and at some point I always get really confused by my own story--but it always ends up working out if I just stick with it and not worry about it too much. You also then have the option of letting another pair of eyes read it to see if someone else is more confused by it than you are. I know a lot of times when reading a book or watching a movie I'll be confused until the end when it all ties together. Sometimes, getting to the end is all you can do. Finishing the story is the important thing.
Yeah, tehuti is right, finish it so it is complete in your mind then reread it yourself and edit it and if you feel it goes on a little then note that down and let someone else read it and note down their comments and then work from there
Do you at least have all the details of the plot clear in your head? Maybe you could write out a plot summary and let a few people read it, see what they think about it. But when I think about it, a lot of the plots I read, especially fantasy or sci-fi, are often very complicated, but they make sense when written and read in full. As a plot summary it might seem very complex, but f you're writing a long book there does need to be a lot going on, to keep things interesting, etc. and it isn't so confusing when reading a long text.
when you've read enough good writing to be able to tell the difference! yup!... read the best stuff by the best writers constantly, so you'll recognize if you're writing crap or cream... compare any page of your stuff to any page in three of the best-written examples of that same genre and you should be able to see the difference...