Flutter GridView.builder how to put children symmetric

i use GridView.builder to build my catalog and my catalog looks bad, how can i put my grid symmetrically :

i want my catalog to look like this :

it is my GridView.builder code:

Widget buildCatalog(List<Product> product) => GridView.builder(
        gridDelegate: SliverGridDelegateWithMaxCrossAxisExtent(
            maxCrossAxisExtent: 300,
            childAspectRatio: 3 / 5,
            crossAxisSpacing: 5,
            mainAxisSpacing: 10),
        itemCount: product.length,
        itemBuilder: (context, index) {
          final productItem = product[index];
          final media = product[index].media?.map((e) => e.toJson()).toList();
          final photo = media?[0]['links']['local']['thumbnails']['350'];
          return Container(
            padding: EdgeInsets.only(left: 15, right: 15, top: 10),
            margin: EdgeInsets.symmetric(vertical: 8, horizontal: 10),
            decoration: BoxDecoration(color: Colors.white,
            borderRadius: BorderRadius.circular(20)),
            child: Column(
                children: <Widget>[
                  InkWell(
                    child: Container(
                      margin: EdgeInsets.all(8),
                      child:
                      // Image.network(productItem.media),
                      Image.network(media != null ? 'https://cdn.yiwumart.org/${photo}' : 'https://yiwumart.org/images/shop/products/no-image-ru.jpg'),
                    ),
                  ),
                  SizedBox(height: 10,),
              Text(productItem.name, textAlign: TextAlign.center, style: TextStyle(fontSize: 20),),
                  Container(
                    width: MediaQuery.of(context).size.width * 0.8,
                      child: ElevatedButton(onPressed: () {}, child: Text('5000 тг')))
                ],
              ),
          );
        },
      );

>Solution :

Try this:

Container(
        padding: EdgeInsets.only(left: 15, right: 15, top: 10),
        margin: EdgeInsets.symmetric(vertical: 8, horizontal: 10),
        decoration: BoxDecoration(
            color: Colors.white, borderRadius: BorderRadius.circular(20)),
        child: Column(
          children: <Widget>[
            InkWell(
              child: Container(
                margin: EdgeInsets.all(8),
                child:
                    // Image.network(productItem.media),
                    Image.network(media != null
                        ? 'https://cdn.yiwumart.org/${photo}'
                        : 'https://yiwumart.org/images/shop/products/no-image-ru.jpg'),
              ),
            ),
            SizedBox(
              height: 10,
            ),
            Text(
              productItem.name,
              textAlign: TextAlign.center,
              maxLines: 2,
              overflow: TextOverflow.ellipsis,
              style: TextStyle(fontSize: 20),
            ),

            Spacer(),
            Container(
                width: MediaQuery.of(context).size.width * 0.8,
                child: ElevatedButton(
                    onPressed: () {}, child: Text('5000 тг')))
          ],
        ),
      ),