I'm going to be late to meet up with my gf on her birthday because I'm baking her a cake
Do you usually bake cakes for your girlfriends?
This is the first and last one and I hope she likes it. You see, I don't want to be too attached to her, she's just a person who is a friend.
Although it is nice of you to bake a cake for your girlfriend, you should still take into account the time it takes. Being late to her party could cause her to be disappointed in you and give her ammo in the future.
I've made my first cake ever and I hope she likes it.
What you are doing is nice, but it is also important to be on time to her party.   Being late could offset her which would make the cake matter less.