It always helps to tell us where you are located. There are hardly any garden questions that can be discussed without regard to location/ climate. What conditions has your lavender been through while it was sitting there? What is your soil like?
Lavender is very slow getting started from seed. In my experience growing it in a cold climate, started from seed in late January, by the end of the season when cold shuts it down again, it might be only six inches tall. The next year it does a lot better. But I would think in two months you would see some noticeable change unless conditions haven't been right for it (e.g. too cold, too shady, too wet). Put a stick next to it and mark the height. It might be that it has actually grown some, but growing slowly it is hard to notice.