If I already got a voucher, help or any compensation from the airline, can I still claim compensation?

If the airline supported all the costs (hotel, meals, drinks etc.) while you were waiting for your flight, you can still claim compensation because these costs are not considered as compensation and regarding the European regulation, the airlines have to provide you with those services.
If the airline offered a compensation and if the amount was less than the fares mentioned in the European regulation and the airline didn’t inform you of your rights, you can start a claim to obtain the whole amount of the regulation fare.