Help - son is not talking

Hello my son just turned 2 in January and since he was younger I knew something was wrong with his speech. He just was never catching up. So initially he said few words but over time lost them or would say words one and never say them again. He knows few sign language gestures and keeps those down. He says a couple words now but not consistently and a stranger wouldn’t make out what he’s saying probably. He’s been in speech therapy for half a year now and there’s been progress in other places but not talking. He babbles like crazy, he’s not quiet at all. He makes noise all day, just not words. He understands what I’m saying cause he responds to things I say to him like “pick this up & go do this” I know he hears me and understands me. The speech therapist goes back and forth about her thinking it’s autism or not and his pediatrician says he’s just a boy and will take longer to talk. Any advice or similar stories?