Sleep regression or growth spurt?

So before 2 days ago my now 14 week old was sleeping anywhere from 4.5 to 6 hours at a stretch at night, now all of a sudden it's like a switch went off and she's back to only sleeping 2 hrs 45 mins or 3 hours. And when she wakes at night she's eating 5 oz at a time. Which is what she eats during the day. I'm a first time mom so this is all new to me. Is anyone else's baby doing this?

Everything I read says Oh they should be sleeping through the night by 4 months but eight now I just don't see that ever happening. I just want a little more sleep!

Any advice or opinions would be great! Thanks!