I Might Be the Asshole for My Sibling's College Fundraiser Mishap

So here's a backstory. I'm the youngest of three siblings, and we've always been pretty close despite our differences in age - my older brother is 8 years ahead of me and my sister is 5 years older. Our family isn't super wealthy, but we've managed to support each other through some tough times by helping out with small things like school supplies or lunch money when needed. Recently, my sister got accepted into a prestigious university that has quite an expensive tuition fee. She started working part-time jobs during high school and saving up for it, but there's still a significant gap in what she can afford versus the costs. So her idea was to set up a GoFundMe page to help raise money from our extended family. I agreed it was a good plan at first - after all, college is expensive and she deserves every bit of support we can offer. But then I started feeling a bit competitive and possessive about how much I contribute compared to my siblings. You see, I have more saved up in my piggy bank from birthday money than what the others likely could spare due to different circumstances they've faced. I ended up donating twice as much as anyone else on her fundraiser page just because it felt like a way to one-up them and show that I care about her future too. The awkward part is, everyone noticed - my brother even messaged me privately asking if there was something going on with him contributing less (which he didn't). This made me feel pretty bad since I know his financial situation isn't great after medical bills from a recent illness. I'm starting to think that maybe what I did was wrong. Did I come across as selfish or like I needed to prove something? It feels strange now thinking back on it - I just wanted to help, but my actions may have inadvertently put pressure on the family financially and emotionally when everyone's already stretched thin. So here's where I'm looking for advice from others: Am I overthinking this situation entirely or was there a better way I could've shown my support without making waves? Or is it common for younger siblings to feel like they need to prove themselves even in these kinds of family situations? I guess what I really want to know is if someone who's trying their best can still come across as the asshole sometimes.