What does fetal movement feel like at 15 weeks?

I have been experiencing "twitching" like sensation on my lower right side of my abdomen and every now and then I feel like gas bubbles in the lower mid section of my abdomen under my navel, my question is is that "twitching" sensation the baby moving or quivering? Does anyone else experience this "twitching" on just one side? I also get hiccups all the time now, does anyone else constantly get hiccups from being pregnant?