As far as I concern, anyone who believe or follow Jesus, believe in what is written in the gospels in regarding to Jesus and his teachings (as well as teachings of others, like Paul, Peter, etc), then you're Christian.
I don't think that just because your church have extra scripture to go with your religion, doesn't disqualify you of being Christian.
I have seen some Christians here, throw around "True Christians", like the way some Muslims use the term "True Muslims".
Seriously, what are "True Christians"?
The Catholics? Are they the True Christians? I doubt it.
Both the Roman Church and East Orthodox Church, both originated with Constantine. There were only Church Fathers, stemmed from the Pauline Christians, before Constantine's time, but I am afraid that the church have changed a lot, more so now then ever.
One of the Protestant sects? I really don't think so. Like it or not, the Protestants all originated from the Roman Catholic church.
The "True Christians" had actually died out when the last of Jesus' disciples died out. Had Jesus or any of the apostles were alive now, they wouldn't not have recognise these being Jesus' Christianity. None of the earlier believers had catherdals, have these customs of rituals and sermons, where they dressed in rich robes.
As others have stated, "Christian" is just a label, and to me, it's worth every little.