Your friend is anxious for you to be serious about your child's immunization schedule. Call your ped's office on Monday morning and ask to come over and get the next scheduled shots. They will tell you when they can fit him in.
If your baby is not exposed to anything, he will not get sick. However, there is a lot of whooping cough going around BECAUSE so many people are not getting their kids vaccinated. Adults get around sick kids, catch the virus and give it to kids who are not vaccinated, and it becomes more and more prevalent. Two moms on this site recently had (or still have) children in the hospital with whooping cough. One is a little baby and that case was/is very serious. Babies who catch whooping cough can die from it.
So, instead of being confused and scared, make the call, get the appointment and get the shot. It takes 3 DPT shots to get the immunity, MG. Be careful where you take baby right now - big crowds and coughing and colds and all of that are bad for your baby, regardless of how many shots he has had yet, anyway. Wash your hands often, eat healthy to keep up your immunity. If you are nursing him, it helps, because your breastmilk has your immunities in it to cover him until he has the immunizations. (Helps, mind you. Not prevents....)
That's my advice. Please get the appointment.
Dawn