Pregnant 10 weeks pp?

I'm NOT breastfeeding and I hadn't started my first period after birth yet, so I decided to test because I was also feeling nauseous and have been feeling cramps but no bleeding... The test was positive. Faint, but definitely positive. I'm freaking out!!! Me and SO have had sex a few times (with a condom). Is it possible that it could be leftover hcg from giving birth? I just had our 3rd and LAST child. I definitely do not want anymore children, atleast for a very very long time.

I have took 2 tests in the past week and the line seems to be getting slightly darker. 😔