Positive pregnancy test 3 months postpartum!

Yes you read that correctly, my 3rd daughter was born 6/12 and I took a pregnancy test this past Monday and it was positive. Went to the dr yesterday for urine and blood test and urine was positive and hcg levels are 1989. I’m going back tomorrow to get blood drawn again and see if my numbers are going up or down. They also did an ultrasound and said they saw a sac but nothing inside. Could be early miscarriage or too early to see anything inside. I wish I opted out of the ultrasound cuz it’s secretly stressing me out...Prayers my numbers go up. I am exclusive breastfeeding and just started getting symptoms today so I hope that’s a good thing. Anyone get pregnant not too long after giving birth?