Is it common for a 14 month old to have only 4 teeth?

Yes: Teeth can be present at birth or not erupt until 15 months. The average eruption pattern starts at 4-5 mo with 1/mo, but later eruption is common & does not mean any deficiency or other issue is preventing it. Often those who erupt later will bring down more than one at a time. By 3 the 20 milk teeth are usually in for all.

Yes.: When the first teeth erupt can vary widely. Sometimes the first teeth can start coming in at 12 months and there may be no more that a few teeth even as late as 18 months.