Hello captain!
Please clarify how you defined that boost has not been applied. Also, we cannot see the troops that participated in the battle, so it's really hard to give any comments about this battle.
XP points are calculated in proportion to the strength of murdered troops and depend on the number of units you kill and their characteristics. The number of gained XP points also is that matter of ratio of power amongst two armies. Player will get fewer points in cases when the discrepant is too big. The similar correlation of offensive and defensive statistics of contesting troops gives much XP points.
Roughly speaking, the more strong units with high upgrade level you kill (e.g. Juggernauts) in a pretty equal battle, the more experience points you get.