There are plenty of reasons not to have children. Off the top of my head are late stage capitalism, environmental devastation, or even simply not wanting to because it's a dumb standard to say everyone should have kids. However, if you want to have children, stuttering and anxiety don't stop you from being a capable and loving parent. For now though, you're 10-20 years from having to have your answer for this question so focus on taking care of yourself.