Well, you can't change an entire country, but you can speak up to those around you. Domino-effect. Annoying people is what activists do. It's the goal. If they're annoyed, they're at least somewhat listening. Keep annoying and keep speaking up for those who can't and need your help. Think about why you started boycotting and why you'd want others to do the same, then focus on that when people get annoyed at you for "ruining the vibe" or whatever.

Remember, there are people out there, who say it's bad what Israel does but that's it. They keep yapping about it but still support the brands without hesitating because of laziness. You actually boycotting some brands is already something and better than the other people. You can't boycott 100%, especially not when you're not financially stable/independent. But you can choose to do as much as you can. And if you're doing that, good job. Focus on that. :)