Breastfeeding & trying to conceive

I am currently breasfeeding my 16m she eats food also but definitely likes the breast when she is feeling unsure, unwell, tired, irritated all the usual...I really want another child but i keep hearing you can't conceive whilst bf? I am trying to wean her onto cows milk but she is having none of it and ends up playing with the bottle. She has never had formula milk. Also I have been with her every second since she has been born we literally haven't spent an hour apart. Please can someone help...? Tips, advice anything welcome! A mummy who wants another baby xx