It seems to me your altenative would be...
1) Commit in May for the whole of next season, and miss out on every game you cant attend, knowing you can shift up to 9 of them via exchange and attend 10 personally.
2) Commit three weeks out, and miss out only on games where your circumstances change in the last three weeks (eg weather) after using up the three tickets you can put on the exchange. You still need to attend 10 personally. Cost per game a bit higher if you dont attend all games.
Sounds to me that your circumstances are exactly suited to the flexi. It may end up slightly more expensive per game, but unless you're really lucky and get rid of all your spares on the exchange, it'll save on the cost of games you knew ages ahead that you couldn't attend.