Sorry can't type thai on this computer.
I don't think to be bilingual slows the speech development at all. I thought it would. My 20 month old baby proves it. He says word that has meaning when he was 15 months old.
I speak 95% Thai to him and 5% English.
My husband speaks 100% English to him.
He understands both languages.He knows heaps of words. I've lost count.
He says about 30 words such as Ban, Deang, Ma (Dog), Ma (Horse), Yai Ja Grandma), Mod, Nei (butter), etc.
English words are No, Nine, Mama, Dadda, B, M, D, New,Ball, Bell,etc.
He knows most Thai alphabet. He knows 1-10 and some English alphabet.
He knows 70-80 business names.
He does what he is told to do such as put the hat on, get the shoes, bring this to me, put the puzzles back, put away his books, put the rubbish in the bin, sweep the floor, etc.