Why do I want kids so bad lately?

I don’t know why I really want kids.Every time I see babies or children, I just think how amazing it would be to teach them and watch them grow. I am not financially ready or stable yet, but for the past few months I’ve been really really wanting to have kids. I feel really maternal, and I have a lot of love, and I have no where to put it. I’m not sure what this is called or if it is normal. I’m only 22, not ready for this big responsibility, but in my mind I still can’t help feeling this way. My life feels like an “empty nest”. I was also thinking maybe getting a kitten/puppy, or volunteering somewhere would help. Has any other female felt this way? I feel so maternal and it’s something I can’t wait to happen… Just wanted to know if this feeling is something deeper than what it is?