it is very simple!
you just need to know two things:
1. the block height these forks happened at (easily found by searching)
2. the time you had your bitcoin (the block height) and the time you spent your coins (if you did spend them).

if you had bitcoin before the fork happened it means you have the fork coin too. you don't need any website to put your address in and search! and that will only tell you one or two forks not all of them which are about 14 or more!

just go to blockchain.info search your address and then click on your transactions to see which block they were included in. if it is below the fork height then you have the coin.