Decades of data suggest parenthood makes people unhappy https://bigthink.com/sex-relationships/should-you-have-kids
Google confessional: Your search engine knows if you regret having kids https://www.salon.com/2017/05/09/google-confessional-your-se...
Many Parents Are Happier Than Non-Parents — But Not in the U.S. https://time.com/collection/guide-to-happiness/4370344/paren...
Having kids makes you happier, but only when they move out https://www.newscientist.com/article/2213655-having-kids-mak...
The depressing reason why having kids doesn’t actually make you happier https://www.marketwatch.com/story/one-theory-on-why-having-k...
Forget about this idea of burden, this is not for you to decide, and if you are serious about that, you should be clear about sharing the workload. And yes, there are also the specific burdens of pregnancy, lactation that you can't share, but also for plenty of women, there is also a reward for those activities. A reward that you as a man can also only reap vicariously. So, for every woman there will be a different balance of perspectives, some value more the rewards and will be happy having kids, others will feel more actually the burdens. Not your business to decide that.
But, what is your business is to understand what is important to you. To understand that if you feel so strongly about it now, it probably won't go away and that you will resent over time, if not right now.
And then, if you have such different attitudes about this matter, maybe, just maybe, it would be best for both of you to free yourselves from each other.