Belgians often don't worry about language issues until the child is nearing primary. My kids' school only start to look at potential issues in the second half of 2nd maternelle (age 4-5) in order to make sure kids are ready for primary at age 6. If your DD is bilingual it's perfectly normal that she doesn't talk at the same time as her EN speaking peers. None of my kids talked much in either language before the age of 2, and my DS2 barely spoke a recognisable word in either EN or FR before starting maternelle. Both my DSs are now as good in both languages as their Belgian and English peers.
If you're still concerned, it could be worth asking at your creche or intended school, as they usually have a particular person they work with.