nuthatch - I use Instead also and the only days I have to change it frequently are the first few - and I'm changing it a Lot less than I was tampons. I agree with Doc it was weird and tricky the first few times - it could be you don't have it "seated" right? I'm only guessing coz that was my problem the first few times I used it too. The best line I read was: remember the first few times we tried tampons - it took a while to get that right too!
Just as a footnote: because of all the research I did on the Diva Cup - I do "reuse" the Instead cup - only 1 per cycle but I rinse it really well with hot water, reuse it and toss it when my cycle is done.