Hi OP. I had placenta percreta which is the most serious type of placenta acreta (the placenta tries to attach to other organs rather than just to the womb).
This wasn't diagnosed before delivery and I did need blood transfusions and, unfortunately, a hysterectomy. However I also understand that an accurate diagnosis before delivery is quite unusual.
The main thing is not to panic. If this has been raised as a possibility prior to delivery then the medical team will be prepared.
In my case, because no-one realised, they did first try to remove it manually and under local anaesthetic which was obviously unsuccessful and also contributed to the need for transfusion.
As your midwife advised, Google is not your friend in this case.
I haven't had any lasting problems because of this and the concerns the doctors had about the amount if blood loss I suffered arose mainly because it took several hours to diagnose the problem. In your case, if you do turn out to have it then at least they can act quickly.
Please don't worry. As your midwife said, things may be different at the time of your next scan and if the diagnosis does turn out to be correct then at least the delivery team will be prepared and can act quickly.
Wishing you all the best.