trying for a baby (After 2 years of being together)

We've been together for 2 years and living together for 1....I work full time and plan on going by to school and my boyfriend works....Recently we had a argument about why I wasn't getting pregnant(I have irregular periods and we both smoke weed) (Don't judge me that's not my question) So he said in the argument that when we first started trying he thought it was me not able to get pregnant because of my irregularity....But noooow all of a sudden(Men 🙄) he says he wants a child before we get too old to have fun still and raise a baby (im 20 he's 22) So my question is should I take him serious now because the first time he said he wasn't taking it as seriously as he will this time....Is it worth a shot ? (this will be both our first child so I'm doing a lot of thinking before I just have my child) thanks ❤️