If you are not 100% sure then I think you have your answer. Have you told your girlfriend you are still having doubts? What about the elders in the hall? Have you spoken to them? If you are having doubts now they will only get worse with time, you will start to feel sick everytime you go in service, sit thru the meetings and pray.
Ultimately this is YOUR decision to make. Don't be influenced by what others want you to do. What do you want honestly want deep down inside? Trust your gut feeling.