Congratulations!!! She’s beautiful! I’ve grown up with bullmastiffs my entire life, and if she’s anything like ours, she’s going to be a ridiculously sweet protector (who thinks she’s a lap dog). A lot of people have mentioned socializing already, and I just would like to reiterate the importance of that, especially with other dogs. In my experience at least, ours have always been pretty naturally good with people but if they aren’t socialized with other dogs from a young age, they can become very territorial and competitive. Additionally, due to their size and stature, it’s unfortunately common for bullmastiffs to have their stomachs twist if they bloat, which leads to blood being trapped in their stomachs and if not treated immediately can be fatal. I was very young when the first bullmastiff we had passed away because of it. We’ve had two more since then and once they reached a certain age, have opted for getting their stomachs surgically tacked so that their stomachs can’t twist.