could I be pregnant again?

I am 5 weeks and 1 day postpartum. When I got pregnant last time I felt super feverish, horrible headache, extremely cold, achy all over to the point where I spent hours in the shower because it was the only thing that made me feel better. Me and my fiancé have been having sex since 3weeks  post partum. We have used condoms every time. So I don't see how I could possible be pregnant again. We use the Trojan bear skin condoms, the only thing I can see is that maybe the one that we were going to use in the shower but didn't maybe had a leak. I mean if got drenched in the shower just the packaging. And we used it the following day. Also one he had under his pillow for a few days we used too not thinking much of it. Has anyone got pregnant using those condoms? I am feeling the exact same way I felt before I found out I was pregnant. Opinions ? I didn't plan for this we thought we were being safe. But I have a new five week old so I'm wondering if it's even possible. Also I Breast feed her and pump bottles for Her somedays. She atleast has one bottle a week to every day depending on the week of expressed Breast milk.1