What you describe sounds like temporary thrust loss due to engine surge/stall because of the bird debris disturbing the airflow. The fact that your engines proved to be undamaged supports this- however this does not explain why the crew were compelled to abort a go-around. I have had four incidents of bird ingestion and in each case there was N1 fan blade damage and/or distortion but the engines continued to run albeit with a loss of thrust and very high VIB indications. With the newer high bypass engines it appears that debris seems less often to affect the high pressure compressor - instead it seems to go through the bypass duct.