hi sue funnily enough i have done exactly the same thing! (lanzarote) and also with easyjet.
Im pretty much sure luggage was extra and i payed it at the time i was booking the trip it comes up when you a paying on the OTB site.
If you check you should find that it will show up on your booking summary they email you. mine says that it includes 1 bag to go in the hold.
If you have a problem or need to add luggage you will need to ring easyjet as your booking wont show up through their website as it was booked by OBT in your behalf.
Hope this helps ive had a couple of really confused moments with OTB