Am I free from zina if I have a monitored, non-flirtatious long-distance relationship with the intention of marriage?

I have a question that I have been thinking deeply about for a long time, and I would really appreciate a clear, evidence-based answer from an Islamic perspective. I understand that having a girlfriend or engaging in extramarital relationships is generally considered haram in Islam due to the risk of zina (both physical and non-physical). However, my situation is somewhat different, and I would like clarification: 1. The girl I am connected with lives far away from me. 2. We do not meet privately or have physical contact. 3. In fact, meeting without a guardian is practically not possible. 4. Our conversations are monitored by her mother, who regularly checks our messages. 5. Because of this, we avoid any form of flirtation, romantic talk, or inappropriate speech. 6. Our interaction remains respectful and controlled. 7. My genuine intention is marriage in the future, not casual or temporary involvement. Given these conditions, I want to understand: Am I still considered to be engaging in zina (or something sinful), or does this situation fall outside of that due to the restrictions and intentions involved? I am looking for answers based on Qur'an, Hadith, and scholarly opinions if possible. JazakAllahu khayran.