Have you ever considered the possibility of having more than one menstrual cup?
Reasons to use multiple menstrual cups
Your body changes throughout your cycle. Even just during your period you may have noticed that your cup fits differently.
1. Cervix position changes
It's normal for your cervix position to be lower during the beginning of your period and high towards the end of your period. In some cases that may mean a low cervix cup (MeLuna Shorty) is only needed during the first few days of your period.
2. Lubrication changes
For the majority of menstruating people the first few days is when the heaviest flow occurs. Generally inserting and removing the cup is easiest when lubrication is plentiful and gets a little less comfortable as things 'dry up'.
For that reason if those changes are noticeable enough to be bothersome you may prefer to go down one cup size for the 'dryer' days of your period.
3. Firmness needs change
The Classic is a super comfortable cup and most users prefer it for general wear. Under certain circumstances the Classic may be compressed during activity.
During those times it makes sense to consider a MeLuna Sport cup. For example I prefer the comfort of the Classic for every day wear but like to use a Sport cup for Aikido (martial arts that involves a lot of core engagement due to throws and rolls)
One thing to keep in mind though is: firmness can not compensate for insufficient diameter. If your cup leaks because the diameter is insufficient it will not seal better by getting a firmer cup.
The firmer cup will help if the cause of leaking us due to the cup becoming compressed.