17 months of living with each other is enough time to know whether or not you would want to get married, provided that marriage is something that you want in life.
By the time you're in your 30's, you already know what sort of age you could 'see yourself' getting married too, and I think it's disingenuous to pretend otherwise by always saying ''one day....''.
It seems as if everyone today, both male and female, has some sort of Peter Pan syndrome, because no-one seems willing to say ''I'd like to be married by 31yrs old, and be planning to become a parent by 35yrs old or so''
Just be honest. If being a parent by 33yrs old is what you'd like to happen in your life, then you need to be able to say it !
It's not so long ago that couples would never have dreamed of living together until they were married for goodness sake ! And I agree that it's fantastic that no longer holds true for most couples, but I do sometimes think we've gone too far the other way......
Nowadays it's more a case of 'living in Never Never Land' than anything else !
It's all ''maybe'' or ''in the future'' or ''perhaps one day'' etc etc
It's almost as if people 'assume' they actually have 'forever' to get married or have kids, when the sad truth is that they don't !
Realistically, men can dither and procrastinate for decades before 'deciding' to get married or have kids, but then they often end up as geriatric husbands to younger wives ( who may well dump them for younger men or have affairs with younger men) and elderly parents to children.
Women, on the other hand, realize that their 'fertile' years are finite, but they often feel 'pressure' to achieve a 'career' first, as well as feel they shouldn't 'pressure' their partners to get married and have children, so they try very, very hard to make themselves 'into' their partners 'ideal woman' in an effort to 'secure' their hoped for future and 'life goals' through marriage/ parenthood etc
But this often leads to very unhappy marriages to partners that are not ideal 
We don't have endless time to live, we have very short and finite lives, and I think many people would achieve many more of their 'life goals' by ignoring what anyone else thinks and being 100% honest with their partners.
It's something I've always tried very hard to do (and broke up with quite a few BF's because I wouldn't do things to their 'timetable' !).
It hasn't always been 'easy', I've cried (a lot !) and laughed (even more !), and it sure has been stressful at times ( I'm talking bout the kids here !)
, but I have achieved most of my 'life goals', including marriage, children, travel and career goals.
Please don't let your own life 'pass you by', simply to please others 