@Ciara ***********
I personally wouldn't take a chance. Once you get through immigration on the Burma and Thai borders you still need to catch a songtow back to the bus station... our songtow was stopped a couple of times by the police checking id's....
Our bus arrived an hour later than expected and we had about an hour to spare... we would have missed the 2:30 bus.
Also, I highly recommend that you pre-purchase your tickets a few days BEFORE you leave... our bus was fully booked