Payed about 0.03 in fees when i transferred from my old imported address to "my bitcoin wallet" in blockchain
can anyone explain why is there such a high size of that transaction
The only possible reason is you have collected a lot of small dust or micro payments and this means you have a lot of inputs when sending the bitcoins from one wallet to another. This results in extremely high fees, now next time keep in mind to not withdraw smaller amounts than 0.02 or above to your wallet. If you withdraw from 0.0005 it is a problem if you do it a lot of times.