Let's get this straight shall we. Being against Zionism is not anti-semitic. Being against Zionism is not to support Hamas. The suggestion of ant-semitism is frankly insulting to anyone who has spent their entire adult life campaigning and fighting (sometimes literally) against racism from all people and against all people. I have friends who are Jewish and entirely opposed to the Zionist project and believe the state of Israel should be abolished. There are many thousands of True Torah Jews who believe the state of Israel should be abolished - indeed they believe the state of Israel is directly opposed to gods will. I despise Zionism and Islamism in equal measure - I DO NOT despise Judaism or Islam, I DO NOT despise Jews or Muslims. This is politics NOT religion.
I don't think anyone would claim that being opposed to Zionism is anti-semitic, for the reasons you outline.
And you are correct to point out that to oppose Zionism is not to support Hamas.
However, it is also true to say that Hamas is an extreme racist organisation that wants to exterminate the Jewish race.
If you read article 22 of its Charter, you'll see it's straight out of the Nazi playbook.
And, despite your being anti-Zionist, the state of Israel was established in 1948 and won't go away. There is no point in wishing it would.
So the Palestinians and Israelis have to find a way of living next to each other.
But that won't happen until Israel believes the rocket attacks on its territory have ended for good.
And I can't believe that the majority of the Palestinians in Gaza want to continue trying to attack their neighbour in that way.