From your first USG report, it seems that both lateral ventricles are enlarged, however your second USG report says that only right horn is enlarged. My suggestion for you is register with some good fetal medicine centre, have a proper congenital anomaly scan to find out other anomalies if present. They might consider you for amniocentesis
to figure out the reasons like genetic, infections etc. Prognosis depends on how venticulomegaly behave as the pregnancy
continues. Post delivery shunting operation is one of the treatment modality.
All the best,