Low breastmilk,baby remains hungry after feed,shall i use supplements?

Keep the baby nursing, don't supplement. By letting the baby nurse for longer periods of time, you're letting her build your supply. It's perfectly ok for her to suck for more than 15 minutes. In fact, most newborns eat for up to 45 minutes or an hour. She'll be attached to you for a couple days, but then your supply will increase and she'll be satisfied after the usual feeding time. So I'm not entirely sure where your doctor is getting his information from.