Mae has been practicing sitting now for a few weeks and I am finally going to call it: Mae can sit up! :) The reason that I am officially declaring this milestone 'met' is that she can bend forward and pull herself back into a seated position. She still topples over every now and again, I still have to put her in the sitting position to begin with, but she is capable of holding that position for long lengths of time and even more officially doesn't like to be laying down now, she is happier when she's sitting. She likes her new perspective of the world.
As with anything, sitting was a learning process and just before she turned 5 months old, Mae did great to sit for a few seconds at a time before toppling over or bending in half. She liked to practice in the mornings in her bed most of all and she did very well to sit up for a few seconds at a time. :)
As she gained more muscle control she got more and more smiley about it and was able to play with toys while she sat up. :) Just in the last couple of days Mae has started to reach for toys and then pull herself back into a seated position. Still not totally able all the time, but she's doing great, for only being 5.5 months old!
Sometimes she still isn't sure about the whole thing but overall she's having a great time with her new view of the world. Next up, crawling!