First, congratulation on quitting smoking and being a new dad! I admire you for wanting to be there for him.
Your weight does factor into the readings on the peak flow meter. Your Doctor can tell you what your level is and if the meter is a good one.
Your lungs sound great in my opinion (but I'm not a doctor). I've been an asthmatic for 25 years (non-smoker) and it's all I can to get my pressure up to 300 on a good day.
So don't fret too much and the doctor can give you a good look-see and calm your worries.
Lupus, Fibromyalgia, Glaucoma, Asthma, Hypothyriodism, Sleep Apnea, Degenerative Disk and Facet Disease, and Allergies
When life throws you lemons....
Pick them up and throw them right back at them! :))