A beta-hCG of 1208 with a 4 mm sac already seen inside your uterus is a reassuring start, and it rules out an ectopic pregnancy. At this stage, a repeat beta-hCG doubling well over 48 hours and a visible heartbeat around 6 to 7 weeks matter more than today's single number. Conceiving after 2.5 years with PCOS doesn't make this pregnancy inherently more fragile.
Next Steps
Your weight of 41 kg isn't a big concern this early on its own. Good nutrition and steady weight gain will matter more as the pregnancy moves forward. Please mention the Femilon you were taking for PCOS at your next visit, so your gynaecologist can confirm it's stopped and plan monitoring suited to your history. A repeat scan in one to two weeks will confirm the sac is growing well.
Health Tips
Please go in sooner if you notice bleeding, cramping, or pain on one side, since that needs checking by your obstetrician right away.