Same for me, mine didn't arrive until the next day, and that was the day I was originally flying. I didn't panic as I had put the flight back 4 weeks, but would've been a real worry if I hadn't.
Although you have 3 entries your total days are only 63 so way under the 157 guideline. The 2 times entry per year unless you can convince the IO you are a genuine tourist, which I think you can do.
I suspect the people being question have had an extensive history of long-term stay in Thailand using visa-exempt entry. This will put a red flag on their file activating secondary screening. There have been no reports of denied entry with a DTV visa.
A DTV holder has a maximum stay in Thailand of 365 days, if they apply for a 6 month extension. Your travel plans are not a problem with your visa. The recent clampdown is aimed at people using visa-exempt entries to stay in Thailand long-term. Visa holders are not affected.