Considering that 2 is the replacement rate. You're contributing to the overpopulation by having more.
Every human needs massive resources. These include land taken away from other living beings and in terms of raw materials such as heating fuel and anything else you can think of, oh you bought a new house? Now you need furniture and where does it all come from? That's right forests cut down. It's so ridiculous at this point that countries like England and Netherlands literally need to import food from less densely populated countries in order not to starve.
Another thing that would absolutely help with climate change is lower population. Less demand for produced goods = less manufacting and growth to meet demands such as massive land clearances.
Someone would say that it doesn't make a big difference but on a large scale, it makes a massive difference and people that have more than 2 children are selfish, interested in meeting their own needs and **** everyone else.