Any bilingual parents /families here who is raising your LO with 2 or more languages?

We speak both Chinese (Cantonese) and English. We speaks mostly Cantonese at home with LO, and teachers speak English at daycare.

LO just turned 15 months. He didn't really speak any first words until 14 months (and even that, I am only guessing those are first words as I am not 100% certain if he meant it).

Yesterday, at our 15-month appointment, they asked us if LO has 5-10 vocabularies, if he points to his body parts when asked about them, and a ton of other things, we said no. At some point the doctor asked us if we were worried about autism. I was like, Wha?? Should I? Heck, LO has the greatest sense of humor, have tons of eye contacts, babbles constantly, picks up books/cards with tons of words and pretend he's reading it aloud.

Doc said we should have at least 20 vocabularies by 18 months. I said I don't see how that's going to happen. Doc said it is going to happen, just like magic. Well, that's what they say when we were at the 12 month appointment that he'd start speaking/ picking up words magically between 12-15 months. I am not seeing magic.

So today, during bath time, I asked LO where is his eyes, foot, nose...etc. in Chinese. He ignored me as usual and does his own stuff. Out of frustration, I started singing the song "Tony Chesnut Knows I Love You" ("Toe-knee-chest-nut-nose-eye...") and point to his body parts. Suddenly, it is like a lightbulb went on. He tried to say something to me with some hand gesture (he kept saying, "dou? dou? do? dah?"), which I don't know what he is saying. I asked him "Where is your nose?" in English. He pointed to his head, I said, no, that's your head. I said where is MY nose? He touched my nose. Now I don't know if that's an accident.

I am just so frustrated I really wanted to quit speaking Chinese and speak English altogether.

So my question for you is:
- when did your bilingual child have his /her first words?
- when did he/she have enough words to start talking?
- were you worried before he/she started talking?
- did you have to take him/her to a specialist?
- Any tips for me?