Bellamy is from the Old French bel-ami (beautiful friend) — historically a male Norman surname now used as a modern unisex given name.
Bellamy 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 Bellamy reduce to 7, The Seeker. This is a traditional interpretive system, not a factual claim about the name.