Hi Brlamova, I have attached with this comment some options for you, if you find these expensive you can also rent homes there of every beach. Locals give out their accommodation on rent at almost every beach, you can try beaches like Morjim and Ashwem. You can also try the shacks at these baches, they are right on the beaches with all the amenities.
Download Airbnb, it has a lot of staying options. Oyo is also good but for family stay, I would say go for Airbnb. It has some of the best staying and budget friendly options.