I am thinking a lot and i cry at times because i think Allah will punish me. I think a lot about these things but i cannot control. Please tell me what to do.
The word "Messiah" or "Christ" means the anointed, and according to Cambridge Dictionary it means "to choose someone to do a particular job, usually by a person in authority". As for the meaning of what you say there is nothing to be concerned. However, since most of the time the word itself is used to indicate the whole concept they suggest according to their religion, I think it's best not the used it. Instead you can make it a habit to use, Jesus peace be upon him, (Best is to use Isa as in Arabic but I assume that could create unnecessary tension between you and a christian you are having conversation with), that is not against the teaching of Islam and moreover will show them actually Islam respects Jesus as a "Prophet".
As I conclusion I would say it's best if you use like I suggested above and even if you say it as "Jesus Christ" there is no harm if you don't really say it to confirm their religion. After all we are responsible for our intentions and asking forgiveness regardless of us realizing if we sinned or not.
"Our Lord, do not impose blame upon us if we have forgotten or erred"(2:286)
Allah knows the best !