Hey christin164,
Thanks for using Apple Support Communities! I understand you have some questions about the space Mail is using on your Mac.
You mentioned you've deleted a lot from Mail already, and that you emptied the trash already. After deleting content, did you empty trash within Mail, and also make sure that none of your deleted emails are hanging out in the Trash on your Mac? If not, you can see how to check that here: Delete files and folders on Mac
Sounds like you may also be experiencing some storage concerns, so I also want to share the resource below with you. It provides some great tips for freeing up space on your Mac.
How to free up storage on your Mac
Thanks again, and have a great day!