This is very confusing and I dont know how to feel. I posted elsewhere and was told it was the wrong group. I'm hoping I can get some help here please

So I had a miscarriage last month. My hcg went to zero and confirm miscarriage on scan. With that pregnancy I was extremely tired and nauseous all the time. Now here is the confusing part we had sex once after the bleeding stopped and my partner pulled out (he panicked and didnt know if it was too soon 😂 men) anyway I then had what i thought was my period that ended 4 days ago a very normal period no different. But since then I have had the same symptoms as when I was pregant? So i took this test! Now I know its positive but it doesn't make sense as my period was exactly the same and as i said we had sex once and he pulled out?