我在GridView.builder中得到空格，同时显示快照数据。我想这是因为我在GridView.builder中应用了条件，所以它留下了空格。有什么办法可以克服这个问题吗？

StreamBuilder(
    stream: fireStore,
    builder: (context, snapshot) {
      if (!snapshot.hasData) {
        return const Center(child: CircularProgressIndicator());
      }

      return  GridView.builder(
          gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(crossAxisCount: 3, 
          mainAxisExtent: MediaQuery.of(context).size.width/1.5),
          itemCount: snapshot.data?.docs.length,
          itemBuilder: (context, index) {
            

            if (snapshot.data?.docs[index]["userType"] == "1" &&
                snapshot.data?.docs[index]["about"] != "") {
              return cardWidget(snapshot, index);
            } else {
              return SizedBox.shrink();
            }
          },
        );
    },
  );