Life / Shipping regularly small parcels from Poland [2]

Hi all :) I have a small business / online shop and to help a family member who lives in Poland, i will transfer part of my activity there by making her pack and ship my orders from Poland. Orders to be delivered mainly to USA but also Europe, Australia, Japan... worldwide!

Does anyone have a recommendation regarding the service to use in Poland? I need tracking number and be sure that the items will be delivered properly but DHL seems very expensive.

For now i use a courier agent who manage very low prices with Express service.
Or do you know a company / agent that can manage this kind of freight / shipping?
It's usually small parcels of 500g, 2 to 3 orders a day...

Any suggestion or feedback is most welcome :)
Thanks!!

Alex.