HI and welcome. I for one do not think you should stop caring for the strays, but I personally don't think you should continue to allow them to roam prior to spaying/neutering. I know it is financially challeging to have all the operations done, but it will be even more financially challenging to care for double and triple the numbers of strays that will look to you for food after a few litters.

Thank you for caring for those who have no one else to care for them.