imovie iphone storage error

I have been using the imovie app on my phone to create videos, and when I complete a project I usually airdrop it to my mac with no problem. Occasionally I get this low storage error, but it's accurate and when I free up space it uploads. However, I recently updated my icloud storage and I have 14 GB general storage available; when I try to upload my video, it says "There is not enough available storage on this device to share your movie. About 5.6 GB space is needed, and 1.5 GB is available. Go to settings > general > [device] storage to make more storage available." I don't know what else to do.