O- blood type

So I have O- blood type. Has anyone else got a Rhesus negative blood type and what are your stories about pregnancy, has anyone ever experienced the situation where your blood mixes with babies blood and what was the outcome?

Every time I go to an appointment the doctor/midwife always bring the topic too attention but don’t really offer anything up until 28 weeks... it’s starting too play with my anxieties too much.