I've known my husband since we were 14, got together at 18, engaged at 23 and married at 26, then fell pregnant less than 6 months after the wedding (due in April) and have never been happier and we are super stable financially etc. Personally I have little issue with the idea of having kids with someone you've known/been with for a short amount of time, but I do think that people should be married before having kids... sidenote: I knew within 3 months of getting together at 18 that my DH was the one, so it is possible to know these things quickly BUT I'd already known him 4 years and we made sure all our affairs were in order and that we aligned on enough stuff to know that our partnership would work even if things got tough and it was hard to FEEL love at any point.
my husband and I could've tried for kids sooner but specifically waiting until after marriage to start because it show commitment and you know they're in it for the long haul then. People used to (and still do) get married after 6 months and have long happy marriages. The key is are your values the same, do you tell each other the truth (and always will), and are your plans and goals the same etc...
You both need to sit down and not only agree that you love each other, want to marry and have children etc... you need to know that your core values and beliefs align so you can raise those children reading from the same hymn book, you need to know you can trust them and that they are fully committed to you and building a family (getting married), do you believe in divorce? Do you want to work towards dual or single income household... do you really want to be a SAHM for example, he needs to be on board with that and you need to understand what it actually means to be running the household while hubby brings all the money in; or do you both want to have a career to maximise income (and maybe you have a dream job), and how will you work towards that and raise children especially before they're able to go to school etc.
Religion, politics, all that stuff is important. You don't necessarily have to agree 100% but you need to be in the same ballpark and willing to compromise and accept differences. Make a list of deal breakers and stick to it. Kids are for the rest of your life... and marriage is supposed to be as well.
So in short, get your serious head screwed on - put aside feelings and romance, because some day you are not going to feel how you do right now because they've been bugging you all week or whatever, and there WILL be rough patches. You need to know if you can join together in a true partnership of marriage - can you work together through all difficulties and struggles for the rest of your life? Can you commit to that legally (and before God if you believe)? If you truly can, then get it done - then have kids afterwards.
If he's not willing to get married before having kids then that's a big no for me. Do not cave and say okay we can have kids first because the burden is fully on you if things go south in the future - kids almost always stay with the mum and without marriage you won't be entitled to any thing from him.
Good luck, I hope that you can discern that marriage will work for you and get married before kids.
Remember: love isn't just a feeling, it's a choice. A choice you make every single day; even if that day (or week/month/year) you don't like that person, you choose to love them anyway because you committed to each other and you know in the long run that you work well together.