The worst that could happen is that they revoke your First Offender status and resentence you on the original charge. That could include jail time, additional fines and community service, etc. It is really going to depend on the judge and your probation officer. The fact that you've been compliant with everything else should work in your favor, but no-contact provisions are generally considered one of the most important conditions and violating it twice looks bad.
You should contact an attorney to represent you in negotiations with the probation officer and judge.
First offender probation is different from regular probation in that, anytime there is a violation of a special condition, a judge can resentence you up to the maximum amount that the statute carries for the convicted offense. If you were only sentenced to one misdemeanor charge than it would be 12 months. If it was multiple counts, the 12 months can be stacked on top of each other if the judge wishes.
Do you know if the warrant/petition to revoke your probation has been filed yet? You should hire an attorney to represent you on any pending probation revocation matter. I consider probation revocations a speciality of mine, so feel free to give me a call. (404) 588-3991