Pregnant again 6 months postpartum

So I just had a baby 6 months ago. I kept getting my period on and off. (Exclusively breastfed baby) I didn’t get my period so I took a few tests and they all were negatives. I took another test 2 weeks after my period should have been here and I got a positive pregnancy test. I’m so scared! I should be 6 weeks 1 day according to my period and I’m not even sick. With both of my daughters I suffered from hyperemesis and was in and out of the hospital. I was SO sick both times right before 6 weeks. So it’s so weird that I’m not sick. I’m also so scared to have a baby so close together. I’m reading there are a lot of risks for preterm labor because the mothers nutrients aren’t fully back from having a baby. And I already have that issue in the first place because I get so sick. On top of that I’m breastfeeding. Has anyone that suffered from HG had babies back to back like this and everything is okay?? I’m so worried. THANK YOU!