Femara is much more potent. Adding Arimidex to Femara is useless. You are using a liquid fem as opposed to pharm grade femara, you can never really know you're getting 2.5mg of letrozole for every 1ml, the research lab may have underdosed the product by mistake. You also can never really know if it's Letrozole or Anastrozole.. Try taking it ED as opposed to EOD and see what happens.. what gear are you using and at what dosages?