There are so many reasons for dental cavities. Dental caries itself is Multifactorial. So it may be due to more or less amount of saliva, texture of saliva, frequency of eating,
sugar intake, etc etc.
So since you are getting more caries and it is going till the last stage that is the extraction of teeth means one thing you are leaving it careless even when you have small caries or your caries are fast spreading which may be due to
calcium deficiency (one of the reason).
Next Steps
Do dental checkup every 6 months so that you can avoid losing your teeth in future.
Fill the cavities which you already have.
You can do pit and fissure sealants if you have deep pits and fissures anywhere.
Fluoride application may also help you.
If you have pain in any teeth go for rct followed by crown so that you won't lose your teeth.
Health Tips
You can use a remineralising toothpaste called TOOTHMIN toothpaste. This will prevent you from cavity attack in future.
Maintain good oral hygiene. Brush twice daily. Floss whenever needed.