So actual etiquette questions:
Is the 6 month anniversary a gift giving occasion?
Is it SS to want gifts in a rel@tionship?
Generally, no, but I think it depends more on how you make your preference known.
Now we are coming up to 6 months and I would kind of like him to show in some way that I mean something to him. Last night I reminded him that next week is our 6 month anniversary and jokingly asked what he was getting me. He stated "nothing" as he does not do that stuff. I kept pushing it as a joke and he jokingly asked whether I was becoming a "high maintenance girlfriend". I don't think it is High maintenance to want the occasional gift but don't expect or want a gift next week.
It was hasty of your boyfriend to call you "high maintainance". However, I think you startled. Your questions may have come accross as a criticism of something he had no idea he was supposed to do. He might have felt as if he was surprised with a "test" that he hadn't seen coming.
If gifts are really important to you, I'd reccomend bringing it up beforehand in a way that makes your feelings clear to your boyfriend, but also doesn't sound like a demand. For your 1 year anniversary, don't ask him what he's going to get you. Instead, a few weeks in advance, open with something like "Shall we do presents for our anniversary?" He'll might agree but he'll probably answer non-committally. That's a good time for you to explain that you like it when loved ones get you presents - it doesn't have to be expensive, just thoughtful. Let him know why a gift would be so meaningful to you. Explain how it makes you feel and what's so special about it. While you're describing this, let yourself imagine how you would feel, getting a special present from him. Let him see that light in your eyes. If he loves you, he'll want to help create that light more often. He'll want to do what it takes to make you feel that way.
The important thing is to remember that other people don't automatically understand the things that have significance to us. If you surprise him a few days before a big event with an expectation of a gift, it will feel like a pop-quiz in a class he didn't know he was taking. But if you simply share your feelings with him, not as a demand or expectation, but as a sharing of information about yourself, and if you give him enough advance notice, then you give him a fair chance to express his love for you. I'm sure he wants to make you happy, and you can give him the tools to feel proud of himself for being able to do so.
Just keep in mind, if he does get you a gift, try to encourage the behaviour. So if he gets you leg warmers because he interpreted your complaints about cold weather as discreet hinting... don't get mad. Thank him for his efforts. And for future events, you may have to give broader hints or even offer suggestions until he gets a feel for your taste. For example, if chocolates are a romantic gift for you, then wait until you are eating chocolate together, and talk to him about how chocolates make you want to cuddle romantically by the firelight.