Take it easy.

That's a falsely formulation. There's no such thing as the “latest transactions”; at least not the way you probably mean it. Each node receives some transactions and keeps it in its mempool. The node doesn't know which one came first in terms of our time zone, anyone can sign a transaction with fake human time zone. The timestamp server essentially works with blocks. The transactions in the memory pool are the ones that happened now. The transactions with one confirmation are 1 block ago, with two confirmations two blocks ago and it goes on.

Thus, each API will return you different transactions, because each node keeps its own version of the mempool and surely the transactions aren't in the same order. You can't know the latest transactions that were broadcasted for sure.

Hmm, to be honest, any free service won't assist you after a while. You should consider temporary anything that is free. Would you find it better if you ran your own node just for the mempool?