Hay, I totally get your worry, lalo na may history ka ng ectopic, that's stressful talaga. Honestly, mas priority mo ngayon ay makakuha ng proper follow-up ultrasound at hCG monitoring with your OB rather than DIY serum testing, kasi kailangan nila makita kung normal ang progression ng pregnancy mo and to rule out ectopic properly. At 4 weeks 5 days pa lang kasi, sometimes the baby is just too tiny pa to see on ultrasound, pero with your history your doctor should be tracking you closely with repeat scans and blood work. Mas safe at comprehensive yan kaysa bumili ka lang serum and mag-worry pa. Please call your OB agad and mention the ectopic history para mas frequent ang monitoring nila, maraming hospitals in QC na may same-week appointments, kaya push mo na.