Negative or Positive Pregnancy?

On 20th nov, I tested using clearblue easy in the afternoon and digital at night and both result were positive. On 22 nov in the morning, I went to polyclinic to confirm my pregnancy however the result was negative and my hcg was like 25?. On the same day but at night, I tried to test using clearblue digital and the result is still positive. I'm abit confused cause never experience this issue from my previous pregnancies. anyone encounter similar issue? need someone to enlighten me. And does breastfeeding affect HCG?😣#pleasehelp #advicepls