I'm 17 and feel as something's missing from my life.

I'm 17 I turn 18 in November and my SO is 19 turning 20 in June. We were each other's first and have been together for 3 years this month! For the past two years all I can think of is having a family and it's taking a emotional roll on me. Since I was a little girl all I could think of was having my own family someday and since I'm older it's coming back and it's all I dream about! It's not the point of having a baby,it's having my own little family! It some how puts stress on me and makes me want to lash out at my SO! He obviously doesn't want kids for another 5+ years and it hurts me so bad that family doesn't mean as much to him as it means to me. I know 17-17 isn't the ideal age and I completely understand what it takes to raise a child and I'm not saying I want to have a baby right now but I wish he would understand how much it means to me and 5+ years cut back 3 years.