Breastfeeding 5 month old

So I been breastfeeding my 5month old but noticed over time my baby would feed but pull away crying so when I check it only dripped out so I gave her a formula bottle while I tried to pump,30 minutes later and nothing in the pump,is there anything I can do,i always offer the breast but seems like she only wants it to sleep on not to feed,sometimes she take to breast then others times she cries.also is it normal not to have a period while breastfeeding as I have not had one at all.