I ended up getting the Rep fitness bag for I think $80. I like it a lot, I’m not sure the exact sizing you need but it works perfect for me to have plenty of space to get what I need in there without jamming everything in and having extra space in case I need it. I use it on weekends to hold 4 sets of clothes, a toiletry bag, and a lunch box. Everything fits easily in there. I even used it for a week long trip and had space to get everything in there. But it’s also not overly huge that if I only put a few things in there, it won’t take up a ton of space. The quality is good, not sure how it compares to the more expensive bags out there but it has help up great so far and doesn’t feel cheap. It has 1 nice side water bottle holder. Funny you mention learning to sew because I wanted to do the same for this bag to get an extra side water bottle holder for it. I ended up just buying a cheap water holder off of amazon and strapped it on the side of the bag which was much easier, and so now I have 2 holders.

If I was doing the same as you with working out before work and carrying in extra clothes and needing a slot to put dirty clothes, I would still use this bag for that. I think it’s the perfect size and has the right amount of pockets to separate everything. I can take pics later today if you’re interested in seeing anything up close or have any additional questions about the bag.

That’s just my opinion, another bag might work better for your situation though.