How long does a typical cold last for a 3-month old baby?

My baby has had a congested nose for more than 2 weeks. I took her to the doctor 1 1/2 weeks ago and he said babies get colds throughout the winter and to just keep doing saline spray and use the bulb syringe to clear her nose out. We've been doing this daily but she's still congested. Has anyone else had a baby whose cold lasted this long? Any tips on healing faster?