Bloody Hell...remind me never to come on MN if I need a bit of support.
Gooseberry, What the fuck are you basing your assumptions about the op's parenting ability on. The fact that a baby is planned does not make it anymore loved or cared for than an unplanned baby.
A low income and a small house doesn't make a shit parent either. I am sure that the OP's initial shocked response was based on evaluating ALL of the factors, including the effect on her other children. I think her trepidation shows a huge amount of responsibility, and an awareness of reality of her situation. She has not taken the decision lightly.
I can't be the only person who has also thought 'fuck oh fuck oh fuck' on finding out I was pregnant with a PLANNED baby. It's a scary, life changing moment and the feeling of responsibility is huge...and then you take a deep breath and get on with it, just as the op is going to.
I also had a very much un-planned baby, when I was very young, and everyone around me predicted disaster. It was the best thing I ever did, and he is now a wonderful teenager. (despite the small house I raised him in) No, I didn't plan, but I bloody well took responsibility, and for what it's worth, my unplanned child is doing extremely well at school, and is very happy and healthy.
Congratulations OP, and the very best of luck.