Welcome to Health Care Magic.
Based on the findings you have mentioned you seem to have propensity for Disc prolapse
at 2 levels. Which is really incapacitating and limits your activity. As far as your planning for second child is concerned. I would like to say NO. Do not take me wrong. I am not discouraging you but i m cautioning you. If you plan for a child there shall be no major problem during the first 3 months as the baby would still be in the pelvic region. But from the second trimester where the uterus
becomes abdominal ,as the the baby grows and you start gaining more weight that might take a heavy toll on your back. That might keep you confined to bed.It might even aggravate your problem.
I would recommend you to first get treated for the spine problem and then plan for 2nd child.
But if you still want a child consult a neuro surgeon or an Orthopaedician , take his advice and plan accordingly.
Hope you got my point
Wish you a healthy life