this is SUCH a difficult question to answer because everyone's bodies react differently to pregnancy and bfing and also because there is a lot of variation in how we bf, how much rest we get, how many feeds per day our los need, how well we nourish our bodies through the experience etc!
i can tell you that MY period returned when i was still exclusively bfing my nearly 6 mo son. you are right about pregnancy before your period shows up again. i am certain other people will share their experiences with you too and will have more advice!
hth!