Often at that age kids say 'I am going out with... ' it can be cute because it is mostly innocent hand holding and just verbally acknowledging that they have a strong like for each other.
Then 'going out' or hanging out in a group can be a good start for getting to know and socialize with the opposite sex.
A lot depends though on their maturity level and how physically developed they are. I have known a lot of pregnant 13 yr old girls that if you didn't know better you would swear they were 18.
I also think that you might be best to look at the other kids her age and on up to around 13 or 15 at her school. If they are into sex and all then it is a little more likely that she could end up going the same route because with what I see teens follow what the others are doing and it isn't necessarily peer pressure but what is considered normal to them.