For the record, OP, I am not that much older than you, so I am not saying this as someone old and bitter who can't relate to a 22 year old, like you seem to think.
Different people like to live their lives at different paces and it can be hard to understand the one sort if you are the other. You are very young and seem to have a focus on getting a lot of "settling down" things out of the way fast so that you can be settled and sorted by a young target age, including children and marriage. Other people would feel like they have missed out by doing so, both in terms of the freedoms that come from a childless life, and not having to view a wedding as purely a practical necessity to be married, rather than an experience that they have hyped up as "the best day in their life". I can relate to your partner wanting a "proper wedding", me and my partner have one DD and aren't yet married, because we don't have the money to have the kind of ceremony I want (which wouldn't be huge but wouldn't be at a registry office), and I have accepted that this makes me vulnerable in the meantime, because it is important to me to have this experience. The fact that your partner is the same and also feels he is not ready for a second child, indicates to me that he is similar, and you are essentially trying to rush him into missing out on a lot of things because you are comfortable with moving at that pace so don't see why it would bother him. But he may grow to bitterly regret that over the years, which would be a sad reality to condemn him to.
At the same time, from a more practical angle, him regretting those things will make him highly likely to decide the relationship was a mistake and leave you with two children, either divorced or unmarried, and a resentful ex who isn't fully invested in his kids because he was pressured into having them.
It is extremely important that you and your partner be on the same page about what pace you want your life to be going, both for your sake and for his. Having to wait for something (you) is better than being pushed into them when you aren't ready (him).