Your problem is that another person goes through your stuff and decided what to throw away without consulting with you. You should tell all people in your house to respect your boundaries and not do anything with your items without asking you.

And as for storing seed, you need two things - redundancy and a safe storage. Write down your seed on multiple pieces of paper and put them in different places. Use mediums like USB, CD, SD cards. Put them somewhere where people generally won't look.