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...
Oregano
seeds 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.