You are trying to learn three distinct things:

1. how to balance,
2. how to steer (while balancing), and
3. how to pedal (while steering and balancing).

Don't try to learn all three at the same time. Just like you would never attempt to juggle three balls from the start. You would first make sure you know how to juggle just one ball, and then two balls, ...

Do this instead:

1. Remove the training wheels. You don't need them.
2. Remove the pedals (but keep the cranks). Learn balancing by itself.
3. Find a gentle slope and go to the top. Hop on the bike and slowly lift your feet off the ground. Do nothing else. The bike will start to move (by gravity). Steer just enough to stay in a straight-line and to balance.

After doing this, you'll find that you learned balancing in just one minute.

Then:

4. Go to any flat surface (away from cars, other cyclists, etc—an empty parking lot, for example).
5. Use your feet to push yourself forward. You'll find that balancing is trivial. You've learned it separately.
6. Now turn gently to the left and to the right, still while pushing yourself by just "walking". You'll see there isn't much to it.

You've just learned balancing and steering. Only pedaling remains.

7. Put back the pedals. Notice carefully which pedal is right and which one is left. They thread differently. For safety, you need to apply quite a bit of torque to tighten them.
8. Now start to pedal. You already know how to balance and how to steer. Pedaling is now trivial. You have likely already used to the motion from exercise bikes.

You are trying to learn three distinct things:

1. how to balance,
2. how to steer (while balancing), and
3. how to pedal (while steering and balancing).

Don't try to learn all three at the same time. Just like you would never attempt to juggle three balls from the start. You would first make sure you know how to juggle just one ball, and then two balls, ...

Do this instead:

1. Remove the training wheels. You don't need them.
2. Remove the pedals (but keep the cranks). Learn balancing by itself.
3. Find a gentle slope and go to the top. Hop on the bike and slowly lift your feet off the ground. Do nothing else. The bike will start to move (by gravity). Steer just enough to stay in a straight-line and to balance.

After doing this, you'll find that you learned balancing in just one minute.

Then:

4. Go to any flat surface (away from cars, other cyclists, etc—an empty parking lot, for example).
5. Use your feet to push yourself forward. You'll find that balancing is trivial. You've learned it separately.
6. Now turn gently to the left and to the right, still while pushing yourself by just "walking". You'll see there isn't much to it.

You've just learned balancing and steering. Only pedaling remains.

7. Put back the pedals. Notice carefully which pedal is right and which one is left. They thread differently. For safety, you need to apply quite a bit of torque to tighten them.
8. Now start to pedal. You already know how to balance and how to steer. Pedaling is now trivial. You are likely already used to the motion from exercise bikes.