To find all the items that had sales within the past 3 months, you'll need to use premium search. If you don't have premium, it's fine to ask a premium user if it's for suggestion purposes. In this case your one is the only one that had sales within the past 3 months, however there's this buy order dump you missed:

https://backpack.tf/profiles/76561198073818313#!/compare/1768780800/1768867200

https://backpack.tf/profiles/76561199026390261#!/compare/1768780800/1768867200

Only 3 keys and some metal match, so the sale won't be usable anyway, but you should still include all sales even if they aren't usable.

Your "21+ key" sale looks more like 22 keys:

https://backpack.tf/profiles/76561199026390261#!/compare/1769644800/1769731200

https://backpack.tf/profiles/76561198275680807#!/compare/1769385600/1769731200

Your 32 key sale looks correct, however for convenience it's better to provide both the seller's and buyer's compares:

https://backpack.tf/profiles/76561198275680807#!/compare/1771977600/1772236800

https://backpack.tf/profiles/76561198199137143#!/compare/1772150400/1772236800

You should resuggest this at 22-32 keys since 30 and 35 come from nowhere