Shadowblade can be upgraded to Silver Edge with a Sange and a recipe. Boots of Travel can be upgraded a 2nd time to let you teleport on players, not always useful but it's something. You can also buy a Moon Shard, which you can then consume to get a permanent attackspeed boost with no item slot. Otherwise yeah you're pretty much close to 6slots, long game and you're last hitting consistently.
To combine items when you don't have space, you need a courier. At your tier supports might not buy courriers, but you can buy one for yourself once you have a bunch of money. It's not very expensive, upgrade it to flying, then you can combine shit easily, just put whatever on the courier/yourself, then use the deliver item and it'll autocombine shit.
If you wanted to 1vs5 though, you would have needed to itemize completely differently. Even then it probably would have been hard. The secret to killing everyone though is crit+lifesteal. You'd want Daedalus instead of Aghanim and Satanic instead of heart, then AC for attackspeed and probably MKB instead of shadowblade for raw damage and no dodge, though none of them bought evasion so a second daedalus would have been fine too. But it's not really an optimal build until lategame so it's kinda hard to itemize like that from the get go. Still if the game kept going, you probably would have wanted to replace your items for better items. That said, 4vs5, not sure you were gonna win regardless.