Ay alam ko yung kinakatakutan mo, pero breathe muna! It's actually super normal na mahirap marinig sa doppler around 11 weeks, lalo na kung first-time mom, sometimes ang position ng baby or ng placenta, or kahit ang angle lang, makakaaffect sa sound, at marami pa ring variables like the doppler device itself or kung paano gamitin. The best reassurance talaga is na nakita mo na last month sa transV ultrasound na malakas ang heartbeat at lahat okay, so yung baby mo is doing great! Honestly, a few of us moms had the same experience kaya nag-worry din kami, pero nung nakita ulit sa proper ultrasound lahat normal lang, I'd say relax and trust na doppler hearing can be tricky sa early weeks, pero kung gusto mo peace of mind, you can always book another transV ultrasound or confirm sa OB mo sa next check-up na walang dapat alalahanin based sa previous scan mo.