The 90 days that the visa is valid for starts the day it's issued, meaning you've got 90 days to use the visa. If you use the visa within that 90 days you'll be stamped into the Country for 60 days. It's not rocket science!
There's no requirement to spend x amount of days in Thailand on the OA visa, you are required to report every 90 days that you spend consecutively in Country
If you didnt get the dreaded red stamp in Laos then you should be fine for another Tourist visa. But be aware the visa doesn't guarantee entry into Thailand.