I'm not sure if this is ISTJ, though ISXJ works and ISTJ may be more likely than ISFJ yes, also, I don't like how you think it's type related if someone has interests that you find "very boring".
I could not follow some parts of the rest of your story, you were too all over the place with lots of irrelevant detail or details not really put together in order that I didn't feel like trying to follow by hurting my head.
But I can add a couple suggestions based on what I've gleaned; firstly, don't be so impatient about her not telling you everything just yet. You two will see over time how well this friendship (?! *) works out. I wish you luck with that but the previous romantic interest(s) could easily get in the way. So the other thing is this, I think that aspect needs to get clarified and resolved.
*: ...doesn't seem like a whole lot of trust and respect being shared there and those are essential for a real friendship, IMO. And when I say trust, I don't mean her not sharing everything yet, that part is reasonable.