Don't get discouraged!
As this is your first venture back after a long stretch, I think the best thing you can do is forget about the scores. Relax and focus on the fundamentals - stance, breathing, grip, sight aligment and trigger control.
Bullseye shooting is 90% mental, 10% physical. And 90% of the physical part is trigger control. Any practice you can get during the week will help. Spend some time dry-firing to watch what happens with your sights when the hammer falls. Find the right spot on your finger where pressing the trigger disturbs the sights the least and memorize how it feels.
Don't be afraid to ask the other shooters in your group for help. Most everyone I've met in the bullseye circles has been very friendly.
And, as you found, caffeine (which I believe Excedrin has lots of) before a match can make things more difficult.
Good luck and keep us posted!