I already bought all the buildings and all the halloween objects. I still got 10 more days to go. ..

I moved all my snow Christmas items to sunflower island

You need to replace low-flower items with high-flower items to keep progressing in the game. For example, the "Dearly Departed" gravesite in the Halloween collection gives 800 flowers in 4 spaces (=200 flowers/sq), compared to a path that may have only 1 flower in 1 space. There are even higher flower items in the regular store. Buy multiples of the high-flower items to keep propelling your game forward and to use limited space efficiently. Since friends/neighbors cannot visit Sunflower Island, that is the ideal place to cluster high-flower decoration.