My youngest of 5 is 3 and is not potty trained and I am not at all worried about it. Actually it is easier for little ones to wear diapers, in my opinion.
Sometimes as Mom's we are in a hurry to cross things off of our lists to move on to another milestone. The list never ends it just keeps going and going.
Try to enjoy each moment and phase knowing that it will all work out. We can all try our best not to judge other Moms whose children may be doing things at different times.
Please don't feel bad if your toddler is still wearing a diaper.It will happen, and if it happens at the right time all will go smoothly.