text picture showed a number that wasnt mine !?

[AC Question]

my girlfreind is abroad, we were in a conversation and i sent a picture, she got it but instead of my name as the sender the message showed a number that neither of us know - she thinks i must have a 'secret phone' and got them mixed up !!!!, i have no explanation, i have a htc one (as does she) and Three my carrier say my outgoing picture message doesnt show on my bill !, but it does on my phone.......HELP please, i soo love my girlfriend and there must be an answer as i did send the message and i dont have another phone...the spurious number is dead if you call it....desperate Ian. reward offered...