Do you have any comments on my number of days in each area?
These cities are all different, but they have some cultural and historical similarities. They are technically in "the same area". I only say that because of your question, not to be snippy. It is possible (depending on travel style) to stay in only one of these cities and make easy, +- 1hr. day trips by unreserved rail to any of the others. Of course, there are plusses and minuses to both styles. The local trains can be crowded, and have, mostly, no real luggage racks.
Check on closing days for museums. It's worth noting that the Mystic Lamb in Ghent is 7 days, but that's not "all of Ghent." I'd take one of your Ghent nights and give it to Antwerp.
I imagine you're flying a real airline from Poland, but note that Ryanair and discounters can use an inconvenient secondary airport, not BRU.
Because I think Antwerp has far more things to see and do than Bruges, I would always allocate the most days to Antwerp. Someone just posted here (2022) that Antwerp has a lot of construction, and some tram lines are interrupted or running infrequently. I haven't been there in several years, so I can't help with that. I have walked all over Antwerp, but it's a big city, and the trams are really convenient.
It's possible to overlook (I mean, accidentally miss) some of the nice things about Antwerp. The excellent Middelheim sculpture garden is a serious trip from downtown. The Meyer van den Bergh museum looks missable on paper, but has a superb small art collection. And it's near the Magdenhuis museum, which is a combination of a leather-wallpapered "mansion" visit and a museum of a Foundling home, including discussion of tokens left by mothers to (maybe) identify their child. And out the other side of the Magdenhuis is a lovely small botanical garden, which leads to the (unfortunate modern architecture error!) newer Theater plaza.
There's a connection between the MAS museum and the (superb) Cathedral of our Lady: From the roof terrace of the MAS, you look down at a scary death's-head sculpture in the pavement, by hot, expensive homeboy artist (Mortsel neighborhood) Luc Tuymans. It's based on a very old work at the Cathedral (which is also filled with Rubens originals.)
I particularly like the unusual pedestrian tunnel (free) under the river that defines Antwerp. There's also a neat turn-of-the-century townhouse development area with about 100 (exterior views only) period homes, ranging from Gothic to Art Nouveau. It's very worth the walking time, near the #2 rail station, Berchem. You can take one tram from the main rail station to Draakplaats, walk the Cogels Osylei homes, and then move on from the Berchem bus and tram stations on the other side. There's at least one cafe to take a break, near the Draakplaats side.
On Sundays in good weather, there are lovely family outing scenes in the public park where the Silvermuseum (now moved to MAS) Castle is. You can also book at the TI for the City Hall art nouveau interior tour, once on Sunday only. I have yet to visit the Sunday only abandoned village preserved from when (20th Century) the Port of Antwerp was moved inland. Incredibly, in several visits I've always overlooked Antwerp's Beguinage.