Galway to DUB for 11:45 flight

Why would you do that yourselves on your departure? On paper your plan may sound feasible but, one snafu and you’ll find yourselves missing your flight. I missed a flight once and it resulted in my son and I taking 3 separate buses and over 18 hours to get from Barcelona to Lisbon. I don’t ever want to miss a flight again.

If carrying on all bags and if you are able to check in before you get to the airport (so the airline knows you're taking the flight) it should be feasible. But I personally would not be able to sleep the night before.

Yeah, sounds too risky and stressful. Are you aware that you will be going through all the U,S. arrival formalities while at the Dublin Airport? That being the case, you really need to be at the airport at least three hours in advance.

Fly out of Shannon.

I think it depends on how much risk you can tolerate. :-) My son, who is in his 20's and lives in Galway, routinely takes the bus from Galway to DUB same day, no matter his flight time. So far...it's all worked out. But he's young, flexible and often flying somewhere for a long weekend, not to get home.

Would this be feasible?

Depending on how you are using 'feasible', one could answer yes or no and be correct.
https://www.merriam-webster.com/dictionary/feasible

1-capable of being done or carried out
2-capable of being used or dealt with successfully : suitable
3 -reasonable, likely

I would not want that stress. In my view you have zero margin for error.

How much is a ticket for a flight tomorrow to your US destination? Multiplied by how many are traveling?
Your trip; your $$; your choice.

Good luck.

(Personally I would go to Dublin late the night before.)

Booked flight departing DUB 1345pm.
The insight everyone's replies provided sealed the deal.