Blood results as well as endoscope testing will Not be reliable since you are already gluten free. More tham likely you may have false negatives do to being on a gluten free diet for the five weeks prior to testing.
The blood tests look for the antibodies your body produces in response to the gluten you eat so when you remove the gluten the body has nothing to form antibodies against so there none for the blood tests to read. Yes you could still have villi damage that can only be seen by doing a endoscope and taking samples of the intestines. But depending on how badly the damage internally was there also may come out negative do to the damage healing which starts within 24 hours of total removal of gluten from the diet.
So your best option is the genetic test unless you're willing to go back to eating gluten for 6-12 weeks and then having the blood work and endoscope done. But still if you do have a gene linked to Celiac you may not actually have active Celiac so also do go to a reproductive specialist if you aren't already.