Even though I've sowed literally millions of seeds
in the past 20 years or so, its still a miracle to me when my seed
trays 'break green' with the coming of the dawn. I realize this is a late reply to your posting, but in hopes you might come across this, here goes...
can be a bit iffy cometimes, not in getting them up, but in keeping your seedling
from damping off. Because oregano can be 'so slow to grow'from seed
, the conditions for healthy growth almost have to be perfect. You are to be congratulated with much back patting on your part.
Generally speaking, perennial herbs, are almost always slower to take off and establish than annual herbs. Especially the Mediterian ones like sage, rosemary, thyme and oregano. While basil plants can reach 4' by the end of summer, you would do well to get 4" with oregano.