Is your neurologist and MS Specialist?
The EMG and LP are just two tests. Until you have eliminated all possible causes for your condition, a definitive diagnosis for MS is impossible. Blood tests can rule out many mimicries, but the "pile" of possible causes still needs to be eliminated. Along with the EMG a VEP (visual evoked potential) is also good. The LP is NOT a specific test for MS and while it is not a required test, it can find specific mimicries.
For MSers who have had an LP, 15% have normal (negative) results. 15% is a large percent; were it 100%, then we would be on track for a specific test.
MS is diagnosed based upon a process of elimination. It can be time consuming and patience can wear thin. Stay strong!