How long do I need to wait before returning to Thailand after using a 180-day multiple entry tourist visa?

I ask for advice from those more experienced than me, I entered Thailand with a 180-day multiple entry tourist visa, arrived on February 5, then left and came back, finally left again on August 4. Now I would like to return at the end of November and stay another 6 months, but more than one person has told me that they could deny me entry into the country because I have already stayed too long; I am an Italian citizen, how much time must pass from when I left the Kingdom (August 4) to be able to return? I am 58 years old but I am not a pensioner, what type of visa do you recommend I get? Thanks to those who answer me