There is no limit to what can fit in your suitcase if you are ok with creating a singularity.
technically, no, the universe wasn’t the size of a pinpoint, the visible universe may have been that size, but the capital-u Universe is very possibly infinite, so it was still infinite back then, just denser. /Much/ denser.
Two points on opposite ends of the visible universe right now (90-something billion light years apart) used to be a millimeter away from each other. Every thing and every where today was there then, just unimaginably compacted, and hot, hot enough to melt matter into an infinite quark gluon plasma. So there were no atoms, no protons even…so dense it would immediately collapse into a black hole today, but with just as much stuff in every direction, there was nowhere for the stuff to condense into.
So yeah, don’t fill up your suitcase that much, or you’ll make a black hole and your socks will be gone, like /really/ gone
I did a bit of searching and the initial size you mention seems to be the initial size to which extrapolation is possible given information we have and that past that point it’s unknowable?
I just put extra stuff into other people’s suitcases before I board and take it out before they get to the baggage claim, I don’t see how people could have this problem???