Finished video won't fully play

I just downloaded Premiere on Sat and taught myself to edit my video - it's 47 mins long!!  I have the finished project and have exported it to H264/Youtube 1080 HD- After HOURS of rendering when I try to watch the MP4 file or the upload to Youtube, I only get anywhere from 10sec to 12 minutes and the the video just stops.  I've made sure that I exported the "entire sequence", and I've exported it at least 5 times and still can't get anywhere past 12 minutes.  Is it because I'm still on the 7day trial period??? I REALLY need this video ASAP.  I appreciate any support/assistance. Thank you.