Hi catchya, you sound lovely to be so worried about your daughter.
Speaking as a doctor, spotting in early pregnancy is extremely common but the problem we have is that in the vast majority of cases we can't find a reason and it is useless as a predictor of continuing pregnancy health.
People who miscarry often have spotting but could have none at all (a 'missed' or 'silent' miscarriage) and usually have cramps and heavier bleeding.
But most people with spotting go on to have normal babies and lots of people with cramps and heavier bleeding also go on to have normal babies. it is just impossible to tell which group someone will be in.
Usually the bleeding is from a small area on the placenta or from the cervix which is much more sensitive during pregnancy. Scans are normal because the baby is developing fine and is oblivious to the bleeding.
Unfortunately you can have no bleeding and a fine scan one day and the next day can miscarry and except in cases of infection or some blood conditions nothing can be done to predict or prevent it.
I can understand why you are so worried. I am lucky enough not to have experienced a miscarriage but at 7+11 weeks I had quite heavy bleeding and I know how scary it is. I stayed at home because I knew that I was safe but that if I was going to miscarry nothing could be done to change it. I was convinced that there would be no heartbeat on the 12 week scan. My son is now over a year old.
I hope things work out for your daughter. The doctors are not deliberately being unhelpful and I can tell you that they are not unsympathetic. But we used to see 10-20 young women a day with bleeding +/- pain and although you feel sympathetic towards all of them you can't continue your job or look after them if you get too upset with each one. Especially since most of them have a happy ending.