Yes, you're slightly off.
GW typically aim for around 4 releases per system each year.
Don't know too much about the WFB releases, so I'll not touch them. But 40k stuff though...
#1: Eldar
#2: Dark Angels
#3: CSM
#4: Appocolypse
The WD blood angels isn't a 'full release' (no new models, etc. for them). It was just a stop-gap measure to show players 'yes, this is indeed the way we're taking all marines now. We've already got 1 SM army this year and we've got too much else to work on ATM, stop complaining to get more). And actually falls in before the CSm release.
Orks, are due for late this year/early next, so really don't fit in with the year you've projected.