you might want to ask the people you booked your trip with. A 1:30PM departure from GPS to the mainland seems like, in my memory, a later flight for sure. It takes 1.5 hours to Guayaquil, where there is a 45 minute layover, before the on-going leg to Quito - another 35 minutes or so. Factor in the time change (+1 hour on the mainland) and it should be a 3.5 hour trip, more or less, by the watch adjusted for time zones. Leaving at 1:30 PM would normally have you in Quito at about 5PM Quito time. Something is fishy there. Do they have you sticking around in Guayaquil for 2 hours?
As LATAM is the only airline flying in/out of Galapagos, the flight availability is less. I checked and currently they are showing one flight, departing at 1:48 pm, with a 47 minute stopover in Guayaquil, arriving Quito at 6:12 pm. I don't know if the day of the week makes any difference. You can check by going to their website.