exporting multiple tracks

When exporting multiple tracks from an initial recording some tracks are very small (15 to 35 mb) the others are 600 to 900 mb. The smaller tracks can be played but cannot be recorded because they are 2 to 3 seconds long. What an I doing wrong. I record the entire side of the LP, Pause and then the second side. Then I go back and silence the breaks and insert the lables.