Difficulty with advisor's specialty I'm a PhD student, nearing the first half of my PhD.

The domain my advisor works in is not really something I love, and I'm more interested in different subjects.
I see now that I didn't invest enough time studying what she does, and it's starting to bite me back.
I didn't study her subject that much because I sort of tried to stay close to stuff I'm more comfortable with, and this results in me not doing much advanced stuff, and not getting results.
But I often regret that what I'm doing with her is not my cup of tea, and try to find ways, or dream of finding ways, to do stuff that's closer to my heart.

I think the situation I'm in right now is kind of a "worse of both worlds", since I think I don't have the full gains of being right in the domain of my advisor, she can't help as much, and we can't really collaborate as much as if I were doing exactly what she does. 

My main fear is that I will spend my time doing stuff that I don't really care for, while losing sight from what I would hope to do.

I'm essentially asking the following question:


  Should I bite the bullet and invest myself fully in doing what my advisor does, or try to reduce damage by trying to change direction somehow?


The pros and cons that I see are the following:

Pros:


There is hope that were I to really invest myself in her discipline, I might come to enjoy it (I have the fuzzy idea that everything can become fun if you go far enough).
Also, maybe I could still direct it in directions closer to my heart (same problems, but approach it the way I like).
Even though I might not like it, maybe once I got a result or two, I could feel OK-er about trying to change subjects, have more liberty.
It might be that the subjects I fancy from my position would actually be too hard, or boring once I started working on them.


Cons:


Big time investment, with risks that it doesn't pay off in terms of results, and enjoyment.
I'm not that good of a researcher, so it might be that I spend my PhD doing that, and find no time later to work on stuff I enjoy more.


edit: My position so far is quite strongly on the "bite the bullet" side since it seems that's the option that would be least regrettable, and I have a pretty good relation with my advisor.
You seem to have answered it yourself, and I'm pretty sure I agree, though it is just opinion. But I'd suggest that you evaluate your options in terms of what will get you out the door fast and successfully rather than "liking" what you are doing right now. You will have the freedom to follow other paths if and when you successfully finish. 

You like your advisor, she seems to be good for you. Too many students don't have those advantages. Working without an advisors advice works for some, but not everyone. 

It might be worth having a chat with her, expressing your difficulties and asking for advice on how to quickly gain insight into what she does. Not everyone knows how to provide that, but if she does, it could help situate you quickly.