Ay anak, napakagaling mo ng nag-observe at nag-advocate for yourself, yan talaga ang dapat nating gawin para sa ating babies. You're absolutely right na sometimes ultrasounds can be done differently, and it does make a difference kung gaano ka-thorough ang sonologist.
Since your OB is also having doubts about that last ultrasound and you're still bleeding, please continue with the second opinion at follow-up ultrasound, yan na talaga ang best move mo ngayon. Ang observations mo about the bleeding color, the incomplete ultrasound, at ang slow development from before ay lahat valid concerns na deserve ng proper re-checking.
Hang in there, mama. Kahit stressful ito, you're doing everything right by being vigilant at not settling for unclear answers. Marami sa amin sa group namin na nag-insist din sa second opinion at natuwa na nagtiwala sa gut feeling namin. Keep taking your meds, stay on bed rest, at abangan ang next ultrasound results. We're praying for you.