Hi, Ann —
There is a difference between Provera and Depo-Provera.
Provera is not an abortifacient; Depo-Provera is an abortifacient.
In this case, the drug is definitely not being used to prevent pregnancy but as a step in promoting it. With Provera there is no need to refrain from sexual relations.
You should get in touch with an expert on Natural Family planning which would be much more effective.