I mean, write back here, and we can try to parse out the dates and see if there is any reality to her statement that you have a chance to be the dad.
If she won't give you a copy of the report, I would treat the whole thing with a lot of skepticism.
Hi, salbarcar, welcome to the DNA/Paternity community. Ask the former partner for a copy of the ultrasound report, you need to see the whole page, the one with her name on it and the date of the ultrasound. Not just a photo. If she can Xerox it and mail it to you, all the better (less easy to fake). When you get it, write back, and say what the EDD on it is.