Condoms

I just had a baby less than a month ago. When we decide to have sex again I want to use condoms as I am breast feeding and not sure of birth control. Plus whatever I use will most likely take some time to kick in.. Problem is that during the almost 4 yrs my fiancé and I have been together we never used a condom. He is more than generously endowed so I think the normal sized ones would be tight on him.