Contraception has nothing to do with poverty/roti!! its pure common sense. If you are poor would you rather have 12 kids or 2 kids?? having 2 kids would improve your chances of providing your children better TARBIYAT....and a better future so they can work themselves out of poverty. Roti is not=to tarbiyat...just because some parents put food on the table doesnt make them good parents...also parents' farz is not limited to providing their children with food. Allah has given us brains to think about REAL issues and REAL problems so we can lead a better life and improve the present. A couple has all the right to decide when and how many children they can have...its legal from all aspects, religious and others.
Often times we forget that the Provider and Giver is Allah(Azza wa jal). Everything happens according to His will. So how could you say having 2 kids would likely improve the chances of them having a better tarbiyah? If Allah(Azza wa jal) wills it then they will have a better tarbiyah and a better life, if He doesn't then even that one child or two children that you have, no matter what you did you wouldn't be able to give them an ounce of a good tarbiyah let alone support them.
So please stop assuming your own means and go talk to a learned scholar who will tell you insh'Allah what the correct ruling is and base your decision off of that. And I will leave you with a reminder. I know of some people who mash'Allah have had their first born but have not been able to get pregnant after that even though they have tried everything and have gotten every test possible done. And subhan'Allah the doctors have found nothing to be wrong with them :) so thank Allah(Azza wa jal) for what you have and you are getting. If He can give He can take and if He does give it then He knows how to provide it.
Every child comes with their own rizq and destiny, don't worry about how you will provide because it's not you who provides but Allah(Azza wa jal).