You can increase freezer space by using sturdy ziplock bags in different shapes and sizes. These are good for sauce-based dishes that would normally go into the ‘plastic containers.’ Always flatten prepared meals and side dishes in the ziplock bags. Remove all air from the bags before freezing the meals. Make sure meals have cooled to room temperature before placing in ziplock bags. I use Ikea bags. They are very affordable, durable and I also wash them and resuse them.
These are the Ikea ziplock bags which come in different sizes. These are very sturdy and I find I can wash and reuse them. These are great for packing meals flat if you are low on freezer room. They come in white boxes as shown.