ahavas Hashem through Torah lishma

In the middle of explaining the mitzvah of ahavas Hashem in last week's parsha, the Ramban cites the Sifri that one should not learn Torah in order to be called wise, in order to sit in yeshiva, or for some other reward, but rather one should learn for its own sake. It seems according to Ramban that the concept of "lishma" is not a din in hilchos talmud torah or in the specific mitzvah being performed, but rather is part of the general obligation of ahavas Hashem. This idea is reflected in the Rambam as well, who cites the halacha of "lishma" not in hilchos talmud torah, but instead in the last chapter of hilchos tshuvah. Based on this, perhaps we can explain "mitoch shelo lishma ba lishma" means that talmud torah or any mitzvah done "shelo lishma" fulfills the basic prerequisite of the mitzvah, but lacks the additional kiyum of ahavas Hashem that is possible had the mitzvah been done with proper motivation.