Lottie is the English diminutive of Charlotte — from the French feminine of Charles, meaning "free man" (so Lottie means "free woman" or "little Charlotte").
Lottie was popular in late Victorian England and is returning fast in the U.K. and U.S. as part of the vintage revival. Today it sits in the U.S. top 800 and is climbing.
Lottie 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 Lottie reduce to 9, The Giver. This is a traditional interpretive system, not a factual claim about the name.