Kids! I thought when I was a kid I wanted them no matter what. In my early twenties I decided I only wanted kids if I could find the right partner. Now I have one. Sometimes my partner is great, sometimes he sucks. I don't care, because my kid is great. She's a joy to be around and gives my life purpose in a way I didn't realize was possible. My whole purpose is just to enjoy reading her a story in that moment. My whole purpose is to feed her when she's hungry. My whole purpose is to look into her eyes. My whole purpose is just to enjoy the moment I'm in, and she accidentally causes me to be fully present so often. It's amazing.
That said, I would say if you're not 80% sure you want kids, don't. Figure out what would get you to 80% first. Financial stability, a good partner, a solid career field, etc.