Worried about being a second time mom😢

Okay ladies, this may make me sound like the worst mom out there, but I can't help but shake this feeling. Praying it's totally normal and everything will be perfect in the end.

My husband and I found out we were pregnant when our first was 8 months old! There were many tears, and they weren't happy tears. BC failed and I wasn't ready to be a mom again. Things have gotten a little easier, but I feel SO GUILTY for bringing another into the world this November when my son will be 17-18 months. I feel like I took away "his time." On top of the guilt, I'm so afraid I won't instantly love this other baby like I did him since he was planned and this little one obviously is not. We haven't even started a nursery yet and I already had his done by this time. Is this normal? I'm so worried about PP depression when I already am so worried about it all. Can anyone relate? Give advice?