I exist in the past, present, and Future. Who am I?

What starts with T, ends with T and is full of tea?

You are my sister but I am not your sister but somehow we are siblings. Who am I?

Sometimes you are so relieved to see me, and other times you run from me in fear. Sometimes I stop you and sometimes I let you go, but whenever you need me I am always a quick call away. Who am I?

The daughter of Maria is the mother of my daughter. Who am I to Maria?