What can i do if I was not fully informed about the contract I signed?

Your position is very difficult.  You signed a document which expressly said that you couldn't have pets.  By law, you are deemed to have read and understood the agreement you signed, and any court hearing the case is unlikely to go beyond this.  Not only is it generally not permitted to introduce evidence of an oral understanding which contradicts the terms of a written agreement which purports to be the whole agreement between the parties, but I'm sure that the lease contains what is known as a merger clause, i.e. a clause which provides that the written agreement contains the parties' entire agreement, supercedes any and all oral agreements or representations, and can only be changed in writing. You may be able to argue that the landlord is estopped from enforcing the no pets clause because you detrimentally relied on its representation that it would not enforce the clause by signing the lease and moving in, and both parties have performed under this agreement (allowing you to have your dogs) for three months, which can only be explained by the oral understanding you claim.  However, I don't like your chances.