Failing to get low quiescent current on 555 monostable
The LMC555 shown in your schematic is a CMOS type and has 3x 100K resistors rather than 3x 5K resistors in the bipolar 555.
It typically draws around 100uA. The old-fashioned bipolar type draws a couple mA typically (there is current draw in both cases that is in excess of the divider chain).
The leakage in Q3 will be multiplied by the hFE of Q2 so you should have resistor E-B on Q2, but that's not likely to be your problem (it would tend to show up as a latent design error at high temperatures).
I'm thinking that the problem is not shown on your schematic and  you have an issue with switching the load with a low-side switch, which is causing sneak paths in your load to ground drawing current. Use a high-side switch and ensure that no inputs to your load are more than few hundred mV above ground.