Actually, you didn't mess up any dates because Tanabata festival is a Japanese variant of what you called the Chinese Valentine's Day (七夕节 qi xi jie). The thing is, Japan adopted the Gregorian calendar even for traditional events once held according to the lunisolar calendar, thus the confusion with dates (note that the nation's most important holiday - the New Year - is celebrated on January 1st in modern Japan, while in China and other Asian countries it falls on the end of January or the first half of February).

Karol:

It is true that we have adopted the Gregorian calendar.  However, we sometimes still use the lunar calendar(旧暦), too.  In fact, Tanabata is celebrated in August in some regions of Japan (not necessary on the exact day on the lunar calendar though...). Same to the New Year.  It has become minor, yet not completely died out and some people are still celebrating the day accordingly to the lunar calendar(*^^*)

Kara, I'm aware of that, I'm just talking about the general rule.　I've heard that they still celebrate the New Year according to 旧暦 in some parts of Amami Islands and Ryukyu.

When I was small, I used to write my wish every year like "I want to travel all over the world". 

By the way, 七夕 is celebrated on July 7th. (In the city of Sendai, it is celebrated on August 7th.) 

i want to have a lot of money