بسم الله الرحمن الرحيم
When you gave three talaqs to your wife and you confirm it then all the three talaqs took place on your wife. No matter if no witness was available at the time of talaq. The talaq took place and the relation of husband and wife came to an end. Now you cannot marry without a valid halalah.
فَإِن طَلَّقَهَا فَلاَ تَحِلُّ لَهُ مِن بَعْدُ حَتَّىَ تَنكِحَ زَوْجاً غَيْرَهُ [البقرة : 230]
Allah knows Best!
Darul Uloom Deoband