We always preg test our weaned heifers when we bangs vaccinate them. Usually find 1-3% bred, we abort them, oops that sounds bad even in cattle, but anyway then we don't have to worry about them. If we lose 1 heifer as a result of trying to calve, the preg testing looks pretty cheap. Pulling bulls doesn't lend itself in our operation very well and I'm sure some of our bull calves that we leave for bulls are breeding these young heifers too. We do pull the bulls later in the fall but the damage has been done by then many times.
Although if you can manage to calve them out at 15 months and then get them bred back to calve in 11 months, well thats a heck of a deal. Can't beat it. Glad it turned out good for you, looks like she will make a great cow!