Well here's the thing. Being Patriotic doesn't mean you MUST be proud of your country. It just means you support the overall beliefs and purpose. And if there is something that you disagree with and have the freedom, well... then you must use your vote and voice to say so. Don't let yourself be censored just because you disagree. But also remember that there very well could be dire consequences for voicing and standing up for those beliefs.
People want simple answers. But the honest truth is everything is so muddled up that it just can't and will not ever happen. So be proud of your country's intentions. Be proud of your country's accomplishments, its growth and lessons learned. And at the same time recognize what has been done wrong in the past and learn from it so you can do better in the future. And in the present change and make up for any wrongs that you can. But more importantly work to change them.