8wks preg went for 1st us 2 wks ago measured 6 wks no heartbeat could not find baby came back 2 wks later 8 wks preg still measuring same size starting to have brown discharge is this miscarrying?

I have to say that the signs aren't great. A 6 week and 8 week ultrasound should be showing a heartbeat and a tiny baby. The discharge could be the very start of a miscarriage and if so it will probably progress to include some cramping. You can ask for blood tests a few days apart to see if your hCG levels are falling. There is always a chance that an ultrasound is wrong, so it is good to include a second type of test.