You are correct, only the loss on the 100 shares purchased in February would be considered a "wash sale".
The wash-sale rule prohibits selling an investment for a loss and replacing it with the same or a "substantially identical" investment 30 days before or after the sale.
You sold all your shares on March 10, so any substantially identical purchase made 30 days before or after that date would create a "wash sale" situation. Your loss on shares purchase in January would not be disallowed.
