I reserved a new phone today!

I reserved a new phone and I will get it late this month. I have been using my phone for three years. It's still working well, but the bettary runs out fast and the storage is almost full. As soon as I said "I have only 2GB.", the staff reacted "Are you really using 254GB now?" He couldn't believe that I used 100GB for videos or pictures. I was thinking about changing my phone in the new year, but I hasitated. This is my first time buying a phone by myself. While my parents bought me a phone by now, since I'm earning I bought it on my own. I was pretty tense, but I felt I became a real adult.