There are no specific laws relating to the minimum age for travel overseas. (I used to know a confident 12-year-old who regularly travelled, on his own, between his parents' home in Sheffield and the home of his relatives in Paris. Some airlines will allow parents to put an unaccompanied 8-year-old on a flight half way across the world, as long as they can prove that the child will be met by relatives at the end of the journey).
If you're 17 and your boyfriend is 18, you could have been married for a year and be thinking about taking your own child abroad, so there should be no difficulties with the two of you travelling together. The only thing that you need to keep in mind is that the holiday arrangements should be booked by your boyfriend and not by you. This is because, at 17, the law regards you as too young to enter into any form of legal contract (such as a holiday booking).
Chris