Keep the things simple without complicating. I know advising is easy, In practical things are different. First speak to your boy friend.. Check whether is he ready for the marriage.. If yes, go ahead and speak to your parents and convince them.. It might take few days or months for them accept your relationship. You should be strong enough to make them understand your feeling.
If your parents agree, you can marry him.. If not continue convincing them.. Any parents would agree after some point of time.
Also ask your boy friend about his parents and opinions, which is the most important thing as if now..
I will pray for you.. Good luck..