Sorry this is a little late!
There isn’t a way that you can know for sure without a test. You can wait for symptoms, but it’s possible to be pregnant and not show symptoms or show symptoms and not be pregnant. If you want to avoid going to the store to buy a pee-stick test, you can go to the doctor’s. It’s a little more private and more accurate, but it might be more expensive (depending on your insurance).
Hope this helps! :)