Am I just being sensitive or is it okay that I’m upset?

So I was in the living room with mom and she was playing Candy Crush Saga like she usually does on Saturday’s. I’m turning 18 next month so I wanted to do a little something special. Especially because the past two-three birthdays we didn’t do anything because she was broke. And I like to plan ahead so of course I wanted ask as soon as possible. But when I asked her he was like “ugh, why do you have to question me like that. I’m trying to enjoy my day off.” And that really upset me. It’s not like she said in a super mean way, but I could tell she was serious. And you may think that I could just wait and ask her about it another time but I’ve tried and it’s always the same answer. When we’re at work, she says she’s too busy, which is understandable but when it’s after work, she says that she’s too tired to talk about it. So i thought the best time to bring it up would be the weekend,

but she doesn’t want to be bothered on her day off

Am I being too sensitive or is it okay that I’m upset?