Anyway, I MANAGED TO GET 2 SUCCESFUL TRANSACTIONS.

I've been trying for 3 hours without success, then I tried that: using MyWtherWallet, I started "spamming" the transaction. I sent it over and over again. 50 Gwei and 200.000 gas limit on the first time. Then 200.001 gas limit and I always increased by one, so that it is considered a different transaction. I did it fast, 1 transaction sent every 3-4 seconds max.

FIrst succesful attempt required 33 tries. On the second one it went through after 10 attempts.