Secret nikaah

I am proposed to my long relation cousin. Both of our parents agreed to our marriage. Actually it is their arrangement. Also with their permission we are speaking via phone. But due to my education my parents don’t want me to do nikah right now. My question is, can I discuss only with my future wife (in shaa Allah) about mahram and give that mahram amount secretly and make this relationship to be halal? Or else am I allowed to keep one or two witnesses only and make this relationship halal? I don’t want the blame on my parents because i don’t feel like its their mistake.