Worried

My cat is 15 months old she got pregnant sometime at the last the end of April, this is her first pregnancy, yesterday she lost what looked like her mucus plug, then she got very vocal and clingy, her breathing was labored and she was kinda pushing, i saw a pinkish bubble coming out and she liked and then it was gone, she hasn't been in labor since, no milk yet, no kittens yet, and she was playing like she used to this morning, I don't feel any movement in her belly either, i only felt them when she was laboring, what's going on?

I am guessing that she passed an empty sac in which a kitten never developed during a bout of premature labor. Based on when you think she mated - end of April - she probably has about 2 weeks left to go. The only way to know for sure is to have an x-ray or scan done by a vet. Otherwise, as she seems healthy, it's a waiting game.