No worries. It takes practice, lots and lots of practice, to look at a situation and judge the camera settings as you raise the camera to your eye. Seriously consider the idea of leveraging the automation of your modern camera, specifically have the camera in AUTO ISO, with a default EC value and the AF defaulted to AI Servo. Then, you just need to adjust the shutterspeed dial as you focus and shoot and the camera adjusts the exposure. After the first burst, develop the skill to look at the exposure parameters as displayed in the view finder without lowering the camera. Quick mental rules like: "swim duck = 500 speed" will prompt you to adjust the shutterspeed while you track the bird holding the focus in AI servo. Then, if the situation changes to BIF, another mental rule of "duck flight = 1600 speed" should ring and you dial in the new shutter speed, all while tracking the bird with the camera in a shooting position.

Consider the following changes:

1. Shoot in AI Servo and use short bursts of 3- to 5-images per burst. Hold the shutter button (or assigned Back Button Focus) to keep the AF system active and continuous tracking the subject between bursts.

2. Judge the minimum shutterspeed needed to freeze the subject. For a surface swimming bird like this wood duck, 1/500 sec would be a better choice, with options to go slower. Leverage the advanced VC (image stabilization) technology of your Tamron lens to hold the image steady with these slower shutter speeds.

3. To simplify the exposure / shooting process, use AUTO ISO in the semi-auto modes of Shutter Priority, Aperture Priority or Program Auto. Specifically for a Canon EOS model like your EOS 7DII, use Evaluative Metering and use +1 EC (Exposure Compensation) when shooting in RAW. Use +2/3 EC when shooting in JPEG.

4. Update the firmware on your EOS 7DII. The current version is v1.1.3 that may help on the performance and focus accuracy of your Tamron lens.

5. Use a single AF point and try for the eye of the bird / animal, if possible. The AF point in this example on the body is reasonable for the distance and f/6.3 aperture, so don't get too frustrated if having a problem keeping a single AF point on the eye of a moving subject.