Classification choice for new film

We chose to have our film certified as 15 because after we read the guildlines, we decided that the plot isn't scary enough, and because the sexualised storyline of rape and abuse is only implied and not shown.
There will be no nudity and the violence is not a big part of the story line. There is also tame language; no drugs or discrimination, there is not any glamorisation of weapons and the behaviour of the film is not that which would be copied or encouraged.
The information which we researched to help us get the correct rating for out film was from the link below:
http://www.bbfc.co.uk/downloads/pub/Guidelines/BBFC%20Classification%20Guidelines%202009.pdf