How soon can I test for pregnancy? Please help.

[Manasacs]

Im 32 years old. I'd been diagnosed with pcos a year ago, however 5 months ago, I was told I didn't have pcos after a scan. My husband & I have been trying for kids since 4 years. On 31st Dec, I had my periods, which lasted for 2 days. On 4th Jan, I had to get an xray done for lower back pain, which turned out to be a slipped disc. After my blood test on that day, my hemoglobin & RBC are low & ESR is high. After this, I realised we'd had sex during my ovulation period last month. I don't have any symptoms except stomach cramps since the last 2 days. Could I be pregnant? How soon can I take a test?