Purchased (2013) 15" rMBP but not sure if I need this spec

I'm new to mac and just out of a whim bought a 15" rMBP (base model: i7, 2.0ghz, 8g ram, 256gb ssd, iris pro graphics). But I'm not sure if I would need this and I'm now contemplating on going with the 13" i5, 2.6ghz, 8g ram, 512g ssd.

I've been wanting to switch from windows for a while and now i've done it. I would mainly use the macbook for web browsing, email, office applications (pages, keynote, etc) and watch movies. I would also use it to convert all my .avi/.mkv movies and tv shows to .mp4. I plan to start using my nikon d90 and upload some photos and maybe use aperture (when i learn how to use it), and that's it.

Portability is a plus but not so much since 4lbs is nothing compared to carrying a pc gaming laptop around. The hard drive space on 13" (512gb) is also nice too, and maybe play app games but not serious gaming since I already have a high end gaming laptop.

I bought the 15" rMBP (brand new) for $270 less than it's $1999 price which equates to the 13" macbook's price. I just want to know if it's worth exchanging it to the 13" and what recommendations anyone has to give me.

Thanks!!

You have a powerful machine that will handle anything you throw at it, but yes for your stated purposes its probably overkill. But as you got a really good deal on the 15, I'm not sure what you'd gain by downsizing other than losing some weight off the machine and gaining storage space. Ultimately, of course, the decision is yours.

If I was in your position (bearing in mind that only need portability a few times a month -- my MBP stays mostly at home connected to a larger secondary monitor), I'd keep the one you have and add external storage for the photo and movie libraries you'll be building.

the larger screen will be better for your photo editing and viewing

+1 for keeping the machine. Even with modest needs, the fact you got a better machine for the same price makes keeping it the better decision.