Will I lose my natural hair if I stop minoxidil?

There are three reasons for hair loss after stopping minoxidil no just one. As you have stated, when one stops minoxidil, the hair that was grown is lost in 6-9 months. However there are 2 other reasons that can not be ignored. Hair that would have been lost were in not for minoxidil use is also lost and finally the balding process simply continues. 

If you have been using minoxidil for a year and have developed minoxidil dependent hairs with this drug, then stopping it will cause you to lose those hairs