No consonants yet- Speech delay?

We went to our 6 month checkup today, and the pediatrician asked a lot of questions about LO's speech. He makes a lot of sounds (high pitched squeels, laughs, makes lower sounds) but no consonants yet. She said to monitor it, and that they don't do speech therapy on babies this young. I didn't realize this is serious enough to need speech therapy? Any input on when your kids started babbling?

Edit- So I'm feeling a lot better seeing these replies. He definitely makes noises (happy squealing mostly) and is very engaged, so I'll hold off on the worry for a few more months.