I converted to Orthodox Judaism two years ago and it went well up until I went on Birthright. I felt silently judged for being a convert even though everyone was outwardly friendly and it had a lasting impact.
I’ve been thinking about you post over yontev, and finally decided to add my few cent’s worth.
I can see two contradictions in your story: Orthodox/Birthright; outwardly friendly/silently judging.
I can imagine plently of readers screaming blue murder over this but I see a disrepancy between someone who claims to have been orthodox and then accepting a Birthright trip. That group is not made for Orthodox people; it is an Israeli front to indoctinate youth with zionism – nothing to do with Judaism. I’m pretty sure the group you were with were not only not orthodox, they were all/mostly/irreligious. No wonder they were judging you.
I am also a ger. When I once attended a university symposium attended by many non-religious students, they couldn’t get over the fact and insisted on quizzing me on subjects totally unrelated to the symposium. Since I am reasonably learned (both in the subject of the symposium and in Torah) they couldn’t very well judge me, but I also felt that several of them resented me, and I’ve come across that iwhen meeting other non-religious people. Some are genuinly interested; some are genuinly surprised (why shouldn’t they be?!) and some are resentful. Occasionally virulently so.
But none of that is sufficient reason to abandon Judaism. I really think you should look a bit deeper inside your own reasons and go beyond the reason you are presently selling. I doesn’t add up; it doesn’t compute.
Best of luck for the future.