Is It Safe To Use Miralax Before Colonoscopy Procedure?

Hi.... I am a 26 yr old female who suffers from ulcerative colitis... I have a colonoscopy scheduled for 1pm tomorrow. My doctor gave me Moviprep and 2 dulcolax tablets as my prep... I got 3/4 of the first liter down before I threw it up... I have already used the bathroom like 5 times though. I was just wondering if it is safe to Use Miralax since Ive already used dulcolax and Moviprep??? Please help...