On Harjatan and Mistress highest dps are most commonly people who save their cooldowns/AoE burst for the adds.
Although those adds still have to die properly configure your Skada, Details to show damage on the proper target. You should feel good for hitting highest on the correct targets. There's always a smart ass who pads better than you.
Spend time at the dummy and study your class/spec. Check the Icy Veins guide, join the Hunter discord (
https://discord.gg/UBNbvz) and always try to improve.
GL HF.
P.S.: Don't panic.