Relationship woes =(

As far as "knowing" that someone is right for you... do you really just know (as corny as that sounds) or does it take time? My ex and I have recently just got back together and he's already asking me about marriage - I somewhat flipped and he said he'd stop pressing the issue, but I know it's still in the back of his head. I'm 22 and he's 29. Any help? I feel like I love him and am in love - but just don't know if it's really "it." And also... my parents don't really think too highly of him. He is a great guy - he just hasn't spent much time getting to know the parents... we've been together for 1.5 years including 1 month breakup. Thanks!