Allright, since many viewed this post and nobody answered the call i will just post here how i solved my problem:

It was all due to the version of the core btc; I was using 0.10.4 where the internal miner is disabled in the source code except for testnet. This was the reason I could mine the first blocks in testnet but not on the mainnet. As for the solution, i just inserted the same parameters as in btc 0.10.4 to btc version 0.9 and used the miner to solve the first few blocks.

In version 0.10.4 the bitcoind was stuck in downloading blocks and could not tell the rpc miner api gateway the GBT (GetBlockTemplate) information so there was no way for external miners to get work from the server. Good thing coffee made me stay awake and crack the problem, hope this helps someone struggling with the same thing!