Am I feeling baby movement? 16 weeks

I am 16 weeks on the dot today and have thought I have felt my baby for the past 2 weeks, this is my first baby so I’m not sure what to expect really. I had some people tell me flutters and some people tell me gas bubbles and for the most part it had felt like gas bubbles and sometimes twitches. I could only really feel them at night when I laid down but I haven’t felt her the past couple nights. Well today I have been feeling a completely different feeling and the best way to describe it is a snake slithering around in my lower stomach. It has been all day today too at random times I just feel a slither movement, does this sound like the baby or am I totally crazy??!