I think your decision comes down to a very easy question: are you happy with the size of a 15" laptop?
If yes, definitely get the 15" RMBP. SOOOOO much more bang for your buck.
If no, well I'd say consider if the 13" RMBP is worth the money, but you already bought it, so I assume the answer is yes. It's a great computer, no doubt, and I don't think you would be unhappy with it at all.
I was in a similar situation. I decided that no, the 15" is too big for me (SIZE, not weight). Then I decided that the 13" RMBP is too pricey for what it is - I'm not willing to pay for it. Gonna go pick up a 13" cMBP today, and feeling good about it!