I've been in a similar spot. I let my boyfriend (now husband) know I was pretty ambivalent leaning towards childfree when we started dating at a similar age to you. We got married in our late 20s and prioritized education and career over the question of kids. We're now in our mid-30s and it's still not the right time professionally or personally. Honestly, some days I think it would be fun to be parents together, but other days, I'm like, lemme lay on the couch with my beer and Netflix at 5pm and eat cookies for dinner. I think it's okay to feel both of those things, sometimes even simultaneously.
You're pretty young so I would say to try not to worry or stress out about this right now, except that you say your boyfriend wants to have kids soon, which seems kind of weird to me. First of all, he's just your boyfriend--you aren't married, and have no obligation to do what he wants. Second, you should be upfront with him now about your feelings--tell him you aren't sure you want kids at all, and may not ever change your mind. If he's not cool with that in any way, he should move on. It will suck, but it will open up both of you to other possibilities. If, however, he can be okay with that--without pressuring you to have a baby, without thinking he's somehow going to change your mind, and without hope that you will change your mind on your own, you could be fine and could proceed to get married (if that's what you want/is a priority for both of you). And you may change your mind at some point, or you may not. Your partner will just have to decide if you're "enough" for him, and will have to make that decision consciously and regularly--reaffirming your commitment to each other as a couple instead of as a family unit may not be as typical in some cultures, but I have to say it's sometimes interesting how many couples stay together "for the kids" and here I am with my husband who just stays with me... because he wants to be with me, and me alone.
If you do decide to stay together, I'd suggest therapy, because this is one of those issues that's pretty black and white, and you need to both be on the same page.