Low lying placenta. And my baby is ok?

Hi I stared bleeding and diagnosed with low lying placenta and retroplacental collection at end of 12 weeks. Was admitted to hospital and dischargevafter 3 days with trapic, proluton, susten. Did complete bedrest till one month all scan showed good fetal heart beat. Till 20 days I bleeded brown blood which was retroplacental collection dissolving. Now I'm week 17 and not bleeding since 15 days. I went for my tiffa scan at 18 weeks today but docter send me back saying she could not see clearly lower segment n only head n legs of baby were visible so she called me again after one day after eating sugary food. Is it a normal procedure and my baby is ok? I'm still on susten 300 mg , iron, calci and cor 3 and after my tiffa scan docter will change med. I'm worried if baby is ok . All my last scan showed good heart beat with baby ok and my down syndrome test were negative