Babies close in age

Is there anybody that has had a child right after there first. How big is the age gap and what is it like. My baby is 4 months old and I think I may be pregnant I’m so scared it took us 7 years the first time so really didn’t think the one time we didn’t use protection could possibly result in me getting pregnant.

I’m also feeling sorry for my little one now because I wanted to just enjoy him for a while before having another