On day 7 of cycle what is considered normal endometrial thickness? ultrasound ordered for 34 year old due to increased bleeding and cramping, bleeding

Huge range: There is a huge range here for possibilities. Day 7 for a regularly ovulating woman with no other pathology--range 5-9mm. However, if you had something like PCOS where you don't ovulate or menstruate regularly then the lining could be much thicker, like 12mm+. Some women with a really thin lining (low estrogen levels) have persistent bleeding and I would expect their lining to be 5mm or less.

Recommendation : Please, discuss this result with your doctor. For proper answer we need to have more information about clinical presentation and patient history