Should I take a pregnancy test?

I am 5 months postpartum. I had my first period last month but now this month I am 3 days late. I am exclusively breastfeeding & my periods were not really regular before baby. We had a miscarriage a year ago & TTC for 8 months before finally getting pregnant again. Now I am thrilled to have my rainbow baby but am so NOT ready for another! DH & I have sex but always use condoms. I am not on birth control. With both of my other pregnancies I had a cold sore & it's the only time I've ever had them & I have one now. I also had PUPPS at the end of my pregnancy & suddenly I think they are coming back!!! I also felt very nauseous Saturday morning. & despite getting 8-10 hours of sleep I am exhausted & just feel weird. I also had some ovary pain over the weekend. I know breastfeeding can make periods irregular so I am hoping that's what's happening. But I'm freaking out. Should I take a test?? Or just assume it's from breastfeeding & stop worrying about it?