Congrats on the increase.
15 new accounts in a year? It might be time to stop applying, let things age, and cull the herd a bit for the sake of Quality over Quantity
When you slim things down it makes it easier to manage, less likely to not be able to spot any fraud, rotate the usage amongst the accounts, and let things mature both from AAOA / CL's perspective.
My Discover which I opened on the same date as you has grown from $4400 to over $25000 and might be even higher with the pending 2 day message from a request I put in yesterday to see if they'll bump it again for the anniversary of the account opening. Thus with a typical monthly spend under $200/mo for some routine monthly bills.
So I got this card 07/27/2015 IIRC at an $800 limit. At the 90 day mark I got it to $1,200 (typical 50% increase they like so much) then in January I took a $500 HP CLI and in February I got an auto $500 CLI to $2,200. Then earlier this month they auto bumped me to $3,200 and now I just did a CLI to see what's what and they gave me $1,500 increase. Now these aren't the $5k increases some of you get but for my TU to fluctuate between 695-705 and the pretty high number of cards I got in the last year it's decent. They like to be one of your only cards but they're still showing a little here and there with no usage (when I was using it they barely gave) even with having around 15 new accounts
Congratulations to you!...Thanks for sharing.