Menstrual cups are often a cheaper alternative than tampons, liners and pads, but they don't always fit perfectly out of the box. Before you toss yours and shell out for another one, try modifying it to be more comfortable.
At $30-$60 each, you might cringe at cutting up your cup, but if it doesn't fit and you're already considering tossing it to try another brand, you don't have much to lose by customising it. As Redditor doctormink points out, snipping the tip and the rim can make your menstrual cup fit more snuggly and be more comfortable. She suggests watching the above video to get an idea of how your menstrual cup works so you can decide where to modify your cup for a better fit.
When making any changes, you should go slowly and cut less than you think you need, then try your cup to see if the fit is right for you, and if not, adjust. You can always modify more, but it's hard to go back once you've made changes. You should also check your warranty and other promises from the cup company, as making modifications may void any replacement guidelines they have.
If you haven't yet bought your menstrual cup, consider which brand may be best for your body type since that can have a big effect on how well it fits before you try modifications.