I would actually say it is more likely that you are Irish than German. You have to understand ancient migration patterns. That particular haplogroup is so specific to Northwest Ireland that it has a greater implication that ancestors went from Ireland to Germany to the U.S. rather than the other way around. It is the haplotype involved with the Ui Niall Dynasty, the legendary King of Ireland.
Having ancestors come from Germany in the 1700s is recent history and doesn't imply a German background. It simply implies that your ancestors lived in Germany at one point, but did not begin in Germany. DNA markers go back thousands of years. This particular haplotype related to the Ui Niall Dynasty starts around 300 A.D. The R1b1b2a1a2f2 haplogroup among those who have submitted DNA is most common in Northwest Ireland and the British coastline. Outside of those areas, that signature is uncommon. Approximately 2% of New Yorkers carry the signature because of the high population of Irish immigrants. You can be sure you are more likely Irish/Scottish/English in your ancient genealogy than you are German with that signature.