Cyst on brain

Elise

Went to my 21 week ultrasound and was told everything was normal but my baby girl has one large and one small cyst on her brain. My dr says not to worry I tested negative on genetic screening including t18 but I cannot help but be worried. I read that the test is only 85% accurate. What’s the likelihood she will be fine? I go back in four weeks. It’s got me crying and loosing sleep 😢 Advice please.