Behavior...is this normal?

My daughter is 21 months and she gets extremely upset of things are out of their norm, for example...if someone else rides in my car with us she freaks out. She also has days where I cant do anything for her, only my grandmother who watches her while I...

work or my husband. I am concerned that there might be something wrong and I am trying to figure out if it is just a stage that kids go through or if it could be something else. Any ideas??

It's quite a normal behaviour.

She's at the age where she's starting to develop habits, and when something changes in her world, it's a big deal.

it could be just habits but it sounds like ocd or a minor phobia because kids dont cry if someone is in the same car its common for some children to develop a social phobia scared of other people she will grow out of it most probably.

Ignore her tantrums. When she sees they aren't getting her what she wants, she'll give up.