I am teaching my DD Chinese and English at the same time. I can tell that she is picking up whatever is easier. She now just start to take interests in math. It’s clear that she is into Chinese and will be learning in Chinese first (It’s so much easier in Chinese than English. All numbers you need to know is 0-10, hundred, thousand, and 10 thousand. Each individual number is much shorter than English too. “lin, yi, er, san, si, wu, liu, qi, ba, jiu, shi, bai, qian, wan” That’s partially why they test better too.) If you are teaching two or more language at the same time, how do you help them to understand math in both ways? To be honest, I had a lot of problems when I learn it in English. lol
Starting young should help 
With my son, I am just doing the same thing in English and Russian. I count forwards and backwards, show flashcards etc. I try to focus equally, or slightly more in Russian (the weaker language). I just plan a ‘lesson’ and do it once in each language.
Don’t force your child to speak. If it is easier for her to vocalise Chinese at the moment, let her,but tell her the words in English at least as often so she hears it and can take it in. One day she’ll probably just start counting in English along with you lol
I face the same problem. In daily life, I teach my girl to count in Chinese. I use LM to teach the number in English. I wonder if she feels they are two totally different subjects.