Bilateral hydronephrosis at 20 weeks

Hi, I had my 20 week scan today and was told the baby has mild bilateral hydronephrosis.  The measurements were 6.2 in one kidney and 8 in the other. I.have to go back in 8 weeks for a rescan to see what happening, they also said its a soft marker for downs syndrome- however I'm still classes as low risk as no other markers, brain lungs heart and neck and hands all measuring totally normal so they said not to be concerned and that if there were more markers then to have amnio test but as low risk and no other markers they didn't seem to think I should have it. I am concerned the 8 weeks is too long to wait, I can't stop crying and worrying and can't feel like this for 8 weeks. Has anyone got any experience with this?