Forgot My Sibling's Birthday Twice in a Row

Hey there, everyone. So I have this ongoing guilt trip because I forgot my younger sister’s birthday not just once but twice in a row. It was her eighth and ninth birthdays last year and this year, and somehow, amidst all the other family stuff going on, they completely slipped through my mind. Now it's like every time someone mentions birthdays around me, I get that familiar sinking feeling and avoid talking about them altogether. My sister’s not mad or anything, she knows how hectic life can be with work and school, but I still feel terrible. I mean, her birthday is a big deal for her, and here I am pretending it's no big deal to cover my tracks. It's just one of those things that keeps nagging at me.