It is easier if you put one generation per line and count. Just remember that "removed" means "generations apart". It is also easier if you use numbers instead of repeating "great".
Her 3rd GGF & your 2nd GGF = brothers Her 2nd GGP & your 1st GGP = 1st cousins Her 1st GGP & your grandparent = 2nd cousins Her Grandparent & your parent = 3rd cousins Her parent & you = 4th cousins She & your child (if / when) = 5th cousins
She is one generation removed from you. That makes you 4th cousins once removed through one of her parents.
To help you understand removed, she is two generations apart from one of your parents. That makes she and your parent third cousins once removed.