Our DDay was 8 and a half years after the A. I could also only give my BS bits and pieces of info, which was very hurtful for her.
All i can tell you is that you have to really dig deep to try to find those answers she is looking for. I think the best thing you can do is try your very best to remember and give your BS evry bit of info that comes to mind, even if you dont think it is that important - it may be very important to her. If there is something she asks that you genuinely can't remember try to explain this to your BS as best you can and let her know that you really do want to help her and you do want to remember, but you can't and as soon as something does come to mind that you will tell her right away.
My BS still has unanswered questions and it is very difficult for her to have closure, because there are still pieces of the puzzle missing.
I took a polygragh for some of the questions and to verify some of the details and there was some comfort to BS with that.
I also tried hypnosis for more details and to answer some of the questions, but that was not very successful.
I think it is very important to show your willingness to try very hard to find the answers, because even if you are not successful she will be able to see that you have been willing to give it your all to find those answers.