[burner31]

I'm assuming you are using the original type bulbs and not the LED's, yes the amps will drop when you're driving with the lights on, no big deal, you should be able to drive all night long like that.
If you would like to crank up the amps when driving with your lights on you can always adjust your third brush to raise the amps, but here is where you have to be careful, if you push to many amps into the battery when you're driving around without your lights on you can boil your water level down in your battery.
So it's kind of a give and take.
From what you have described with your amp readings I'm not seeing much of an issue.
If you can drive around at night and it starts in the morning...you're doing good.
Others will chime in, and most of them probability know more then me.