Flo having spent a lot of years around older people, I'll say that your nurse is correct, if you don't get up daily and often enough, you'll loose strength in your leg muscles fast and will be reduced to using a walker or wheelchair in a short period of time. Being bent over a walker will only make your back feel worse.

You might want to try using a polyurethane back brace, it's just a long rectangle piece of polyurethane with velcro on one end that you wrap around your midsection. It'll give your back some support which should make it easier to walk.

Over the years I've had both bulging discs and pulled back muscles and that polyurethane brace has really helped me with standing.