You might wanna load it with fuel and do a dry run without food. Might find it a little less stressful.
Also briquettes will burn at a slightly more steady temp than lump. 10-15 lit is plenty. Personally I use only lump. I like the taste it imparts in the food better.
It sounds like your chasing temps, as others have stated. I like to allow at least 20 mins between intake adjustments. This gives your uds time to settle in to its latest adjustment. :)
UDS, mini wsm, 22.5" weber kettle