I don't think you're crazy--it's normal and I think you'll eventually know what's best for you.
I didn't have the baby fever for a long time. I couldn't even imagine myself with a kid. And Babies and kids never seemed to like me, either--someone would hand a perfectly happy and calm child to me and the minute I touched them they'd start starfishing--you know, spread out, wiggling and screaming. I figured babies just weren't for me. Even after I'd met my DH when we were 23 (got married at 25, just before we turned 26--it'll be 2 years in May!) I couldn't imagine it. I already had my degree at 21, had a great, stable job even though living in NY is stupidly expensive. DH was still in school finishing his degree...
then all of a sudden 25 hit me like a ton of bricks. I just felt
different. The baby fever crept over me slowly...I was meeting pregnant women everywhere, my sister was pregnant, boss was pregnant, women in my dance company were pregnant. Even my parents were asking when I'd be giving them grandkids! I fronted--still am, at least to my parents--that i didn't want kids. But I have IMPOSSIBLY strong baby fever! DH and I have finally started TTC#1. I am ready. I was holding out for grad school for awhile, but only because I felt like I "should" go, not because I wanted to go. It's been 6 years since I finished college and I haven't been the least bit interested in grad school yet. people keep telling me things like if I don't go back now, I never will. That's a bunch of b.s.--I'll go when there's something I actually want to go *for*. I'm doing a 10 month weekend program right now, but i don't want to do more than that. And I love my job, but have been here almost 4 years and there's no higher position for me to get other than the one I don't want. I want to start my own business eventually, and I am working on that slowly but the way I really see my life moving right now is towards having a family. My sister is 31 and has 2 kids--my 7 year old niece and my 1.5 year old nephew. I feel like if I wait any longer, I'll be doing it now for me, but for other people's expectations of me.
It's a little difficult for me also because I live away from most of my family--they're mostly in the south. My cousins who are my age are also married. One is pregnant right now, one, the male one, and his wife just lost their first baby at 6 months in utero--it really hit the entire family pretty hard (my dad's one of 7--I have 16 first cousins on that side). Everyone in my family in my age group or older, except for my one gay cousin, is married, pregnant, engaged, or has kids, or some combination thereof. That makes sense to me.
On the other hand, all of my friends here who have gone to Ivy league or elite colleges and are into the NY rat race and all of that, or are LGBT and my age, are not even anywhere near thinking of babies--I am all alone! Whenever I mention it they're like "oh boy, can't imagine that!"
I am rambling--sorry! I guess it struck a nerve. The last thing I'll say is that reading Rebecca Walker's book Baby Love
last summer confirmed something for me. She talked about being the child of a famous feminist and all of that, and getting all the great career encouragement and so forth, but no one ever really just talking to her about motherhood and how to plan other aspects of her life like she planned her career. All of the "you can do whatever you want" never told her that fertility was finite.
That said, I have a boss who just had her third child at 42, so I know it varies person to person. I also know that I am SO ready to have my kids now! Even with all of the mixed messages--some people are like "oh god, 27, you're still a baby yourself"--so I can only imagine what you're getting at 20. And other people are like "you're not getting any younger, tick tock!"
I think that after awhile, you'll just become sure enough of your own conviction about it, and figure out what you need to do to make it a reality for yourself--aside from the obvious things you need to do to make it happen