M27, girlfriend is also 27. We've been together for 4y and I had figured we would probably get engaged soon. She told me last week that she's pregnant, and I didn't react super well. I basically said "shit" and freaked out a bunch. She's on the pill and obviously it's not 100% but I was still taken very off guard.

We had the conversation about what to do about it and she wants to keep the baby. And so do I, I think? I mean I always wanted kids with her, and the idea of aborting our baby is upsetting to me. I think if we aborted it then when we did have kids together I would always think about this one and wonder and feel selfish. At the same time, I just feel so stressed and freaked out when I think about this. 

My girlfriend is upset because I am not happy about the pregnancy. I tried to tell her that of course I will love the baby when it comes I'm just upset because it wasn't how we planned our lives to go? She feels like since we've committed to having the baby that means I should feel happy and excited about it. But in reality all I've been thinking about all week is how it feels like we super fucked up even though we didn't really do anything wrong. We talked last night and she got really upset with me and accused me of not even wanting the baby.

AITA for not doing a better job of hiding my unhappiness about the circumstances from my girlfriend when we both agree and have decided that we want to have the kid?