It is common for the Filet Crochet to appear uneven when you are crocheting a project. The width and length will look distorted to each other with the length being to short and the width appearing to wide.When you are finished all you need to do is block your piece. That just consists of soaking it in a starch/water solution for a few minutes stretching, shaping and and pinning it out on a bed. I look for rust proof pins. From experience the cheap, pins will rust and leave rust stains on your work. Below is the recomended starch to water solution for lace doily's. You can adjust it to more at any time. I have found that I like a little heavier starch at times depending on the size of thread I have used.
1 part Starch to 6 parts water
I always use towels on top of my mattress to soak up the starch. I have even used a pressing cloth and dry iron to expedite the process. I have had many filet pieces that I thought were ruined until I blocked and stretched them lengthwise. They always came out beautiful.