@HazelBuckley @mzimmerman is 100% correct, you really need to reach out to your school's Canvas or IT team. One suggestion I might make though, if you can look at your computer's browser history and screenshot any evidence of you submitting the assignments. If it will let you revisit the links showing successful submission (guessing it will not but it is worth a try) and screenshoot that, that would be very helpful.
Canvas does log basically every click you make and your school's Canvas administrator can see those logs which does indicate when you are on the submission page of an assignment. It is possible you lost network connection or something went wrong during submission so it appears to work for you but not on what the teacher can see. This is very rare but I have helped students/teachers show that a student did access the submission area.
Good luck!
-Nick
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