Aw congratulations sa pregnancy mo! Yan talaga ang first movements, parang bubbles, flutter, or gas lang talaga, kaya confusing haha, isa sa mum friends ko thought she was just bloated pa lang at 18 weeks At 20 weeks you might start feeling more distinct movements na parang light taps or waves, pero bawat mama and baby different so don't worry kung hindi pa super obvious, some of us didn't feel clear kicks until 22-23 weeks pa, especially first time. Best talaga to ask your OB about it sa next checkup para ma-assure ka, pero sounds normal yung feel mo ngayon!