Forgot My Sis's Birthday

So I totally spaced my sister Jenna’s birthday. It was yesterday, and I only remembered because she texted me about it this morning. Now I feel awful but also a little relieved since I have an excuse to get her something nice now without the pressure of a tight deadline. But honestly, how could I forget? We’re twins and I'm supposed to be protective and all that. What if she feels like I don’t care or something? Maybe I’ll just send her a big card with lots of balloons and candy...but what kind of candy does someone like Jenna even like? This is stressing me out more.