Thanks all for your comments and replies. When I got this card 3 years ago. I started with 2500. Also I didnot know how to increase credit limit. After a year and half, I got my first increased to 3200. Until I found out about this forum, I learned a lot. Thanks all.
PS: i used to use this card to pay for tuition about 17k and pay in full by the end of cycle, so i feel less guilty to ask for credit limit increase. Haha
EX: 704, EQ: 728, TU: 702. AAoA: 2.8 y
Amex Business Platinum: NPSL, Chase Riz 24k,Chase United Club 20k, Paypal MC 40k, Discover 22k, Citi Advantage 31.5k, Amex BCE 33k.