Severus helped Harry. There is not a plainer way to put it. He may have done it grudgingly, but he was willing to do it. He risked his life for his. And that is not for the weak of heart. As Dumbledore put it "If you loved Lily Evans, if you truly loved her, then you way forward is clear." In other words, he has a duty, and what he should be doing to help is obvious. He needed to protect Lily's son.

Now, Snape might have been many things, but he was never a coward. He looked after Lily's son. He did not do it happily, and he most definitely was not nice about it, but he did it. And that is what matters most. He did it. He sacrificed his whole life to help protect the memory of Lily. Here are 3 times he helped Harry:

1) The sword and the silver doe. Without the swordof Goddrick Gryfindoor, they wouldn't have been able to destroy a Horcrux

2) He showed Harry his memories. Risking embarrassing himself was not important. Harry needed to know about himself and how to end Voldmort. A very noble last act.

3) When he made the decision to protect Lily. This saved Harry's life!