Shar, breastfeeding is an effective contraceptive for the first 6 months only, and only if:

- the baby is exclusively breastfed, ie no formula or solids
- the baby feeds at least once through the night
- AF has not returned.

In your case, the baby is not exclusively breastfed so you could fall pg. No-one can really tell you your chances, it is different for everyone.

To answer your other questions, feeding during the night maintains a higher level of hormones in your body than just feeding during the day, so therefore this is helpful in preventing pg. It is also possible to ovulate before menstruating, therefore falling pg before having an AF is possible. Research has shown that the longer it takes for AF to return after the birth, the more likely it is that you will ovulate first.