D.M.
Sounds totally "normal" whatever that is... so don't stress! For our daughter, consistency was key. We took her out of diapers completely (just pull ups at night). This suggestion came from a mom of 7 - so I figured she knew what she was doing!!! Seems to work and made sense that once the diapers are gone, there is no confusion, and hopefully just a few messy days.
We also made a BIG deal of underwear and then rewarded her with silly songs, tons of recognition and m&ms when she told us she had to use the potty. We never "punished" her for accidents, made her sit in dirty pants or clean it up alone. Keep it positive and be patient.
As far as your mother in law goes - just try to ignore her pushiness...I'm sure that's hard.
Enjoy 3... my daughter just entered her 3's on Saturday... such a fun age... most days!