I am the same way. Ds is now 5 1/2 mos, but has been a non sleeping, cranky, comfort nursing baby from the start, and like you, even leaving once in the morning would throw our whole day off. I like to be home, and always have so much to do or that I want to do that I stay busy. DH has said on more than one occasion that I need to get out more, but I am happy and feel I can give DS better and more attention than I could being out.
I saw that you mentioned you are a helpmeet to your husband, and if you are familiar with Created to be his helpmeet, she actually says in there that women arent supposed to go from house to house, which I interpret as staying home with the kids, keeping up on affairs of the home. My mom comes down to visit once a week and I think she gets cabin feverish when shes here, but I like my suddenly slow paced lifestyle. Like someone else said, they used to call us homebodies, now we would prebably be "recluses." If your happy, keep it up. I have a friend who is the same as me, she just lives a couple hours away or I would spend way more time with her

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DO WHAT MAKES YOU HAPPY AND WORKS FOR YOUR FAMILY.
Momma to sweet little DS who has his first tooth! and wife to one amazing guy!