I'm really confused. From what I understand, she wanted the front done and you quoted "X" amount. She agreed and then wanted to add on more and have you do the side, but you never gave her "Y" amount????
It really sounds like shes working you, and she wants it done for next to nothing. Simple pictures in the mind take time to make. For the future, never show your hourly cost. It opens up a whole other can of worms. Give your estimate and stick to that price....or pad the number a bit so you can lower it and give them a "deal".