Just by asking the question, I think the OP knows the answer. It's interesting that no one every asks whether 9mm, 40S&W or .45 are adequate defensive rounds (in defensive loads). It is also interesting that few people ask about .25acp, 22LR or even .32 acp when it comes to a self-defense pistol-round.
However, there are lots of inquiries about .380 - is it good enough or too weak. Its similar to the question of whether you can use 5.56 to hunt deer. The one difference is that there really is no good justification to hunt deer with 5.56, even thought it is sometimes done effectively. And, "it's all I can afford" doesn't cut it - obviously someone hunting deer is already spending money on gear, license, stand, etc. - there's no reason you can't get a scoped 30-06 for $300 (I did), which is about the cost of a used tree stand plus license.
On the other hand, concealment and ease of carry is a valid reason to consider .380. I do believe that if you question whether .380 has enough punch for self-defense, then it probably doesn't.