Romy is the diminutive of Rosemary or Rosemarie — combining Rose and Mary.
Romy is enormously popular in the Netherlands and Germany. In the U.S. it entered the top 1000 in 2017 and is rising fast.
Romy does not currently appear in the US Social Security Administration's top 1,000 girls' names, so we don't publish a US rank or birth count for it. That says nothing about the name's standing elsewhere in the world — only that it sits outside the ranked US data we rely on.
In Pythagorean numerology the letters of Romy reduce to 8, The Visionary. This is a traditional interpretive system, not a factual claim about the name.