URGENT! PREGNANT CAT?

My kitten Bella is pregnant! I don't know how long exactly though. But I don't believe her due day is that close. Bella is a kitten, that went into hear and got pregnant. Her belly is so big. She likes to nurse on this fuzzy blanket I have. And today, like 5 minutes ago, she was hollering at the door for me to let her in. She jump on my bed, and laid down on the blanket. She looks so uncomfortable and always wants me by her and to pet her. She keeps lifting her hind legs and originally was laying on her hind legs, with her tail up a little, and looked like she was pushing. What's going on? Should I be concerned at all? Could she be practicing or something, or is she possibly close to her due? Help, I googled it but I can't find anything!!