I am certain that the reason why her memory stops before the time she met you is because あの子の記憶が あなたと出会う前で 止まったのは

Nevertheless,

Thank you, Yukari.

But it's really okay

Just maybe, something might make her remember everything that has happend until now.

Besides,

don't you think there should be time for you to relax as well, Reimu? でも もう楽になっても良い頃合じゃないかしら -> This was really hard for me to translate... Someone might be able to come up with something more interpreative (preferably with a mention on opportunity/good time) 霊夢

that child must be feeling that meeting you was the best thing that has ever happend to her. きっとあの子が あなたとの出会いを 最高の運命だと -> gretest destiny/fate -> the best thing 感じていたからよ