It's definitely possible that these are the side affects of the new pills...I have switched birth control pills a few times, once because I was breaking out really bad, once because I was gaining a lot of weight, another because my periods were heavier than normal so pills can definitely make a lot of things in your body change. If you are having issues with yaz I would call the doctor and tell them and see if they can switch you to something else that won't make you feel this way. As far as your period not being on time it's probably more than likely it's because your body is trying to adjust to the new pill.