No, it's not too late....but it is going to take a big effort on your DH's part!
If you are in England and he is the only day to day source of Portuguese, he is going to have to adopt OPOL pronto and stick rigidly to it. OPOL means "one parent, one language" and henceforth, your DH needs to speak ONLY Portuguese. Always! Without fail!
Then there are some other tactics you can implement as a family:
Henceforth, all DVDs need to be in Portuguese. Idem all spoken word CDs that tou might listen to in the car or in the house. No more CBeebies! Get relatives to send DvdS from Portugal or buy them from Portuguese Amazon.
Trips to Portugal whenever possible. Trips from Portuguese family as regularly as possible.
There must be computer games / sites dor children in Portuguese which your DH can share with your DD.
Lots of books in Portuguese. If you speak Portuguese well enough, I woukd consider having you read in Portuguese, too, even though you are not a native speaker to increase exposure at the beginning. Unless you have a quite excellent level, though, I woukd not recommend you speaking Portuguese.
6 is definitely not too late, but with limited exposure, in England, it is going to take some energy and detemination.
Good luck.