Baby has an ongoing cold? How long do they last?

Basically for like i think 2 months now (my daughter is 3 months old) shes got a cold. But not like sneezing alot, coughing or even a runny nose.

She gets boogies yeah but their not runny, they're just thick and i use saline mist to soften and boogie sucker to remove. And that's usually when she wakes in the morning and before bedtime at night, all day shes clear. And when she full fledge cries you can hear the mucus congestion in her lungs. I had the doctor check her out last month and she said for the boogies to just clean them out and that the sounds we were probably hearing were from her nose (definitely her lungs though) then she listened to her lungs with a stethoscope cuz i asked and had no complaints. She did say if she gets congestion then to just sit her in the bathroom with me; with steam for her to inhale and that was all. She's a good pediatrician though so i know she wasnt being an asshole or anything. Baby hasnt even gotten any fevers either but was just wondering what was considered normal?