This could be a good story, but I think that yes, you are pushing Idrial into Sueishness simply by trying too hard not to. Joining the Fellowship as well... I have to say, I think there are too many Tenth Walker stories now. I used to write them, but several friends told me just what was wrong with them, so I gave them up before I uploaded them. Idrial sounds like she could be an interesting character, but the War of the RIng is probably not the right setting for her. I'd be much more interested in hearing her backstory- how did she come to be adopted by Cirdan? Many Elves, once they have reached adulthood, are fairly independent, which means that Idrial would probably have been quite young- less than a hundred years old or so if she wasn't yet an adult.
It also looks like Legomance is on the cards, which is another no-no in my book. He appears in far too many stories to be believable any more. If you want to write romance, you could always write another original character for Idrial. I think quite a few people would prefer that to yet another original character after Legolas.
I hope this was useful to you, because I think you could be a really good writer if you thought about your settings a little bit more.