That is not premature ejaculation. That is just him getting off really soon into things. Premature ejaculation is before he actually orgasms. It's not a lot or anything, it's purpose is a lubricant, but it does have semen in it, so yes it can get you pregnant. He will not notice the premature ejaculation...So what I mean by that is he has no control when it will come out, and neither of you will notice it at all. The white discharge, if you only have this when a condom is used, then it from you, but if this happens when you do not use a condom it is probably from him. I have had that before, a couple days ago me and my boyfriend had sex for the first time without a back up (i am on the pill as well). Usually he pulls out, but he didnt this time and so afterwards when I stood up from the bed, I felt this huge gush which was his seamen coming out of me. So you would probably know if it was from him or not...
Hope I could help a little :)