Missed my cycle

So my last period was on 8/3. I had sex on 8/22 pull out method was used. On 9/14 I went to ER with flu like symptoms back pain n stomach cramps like I was going to get my period yet here it is 9/17 and still no AF . I CHECKED my CM and it was a lot of clear sticky mucus like snot. In the ER my urine n blood test both BFN . Could I still be pregnant? Was it too early?