I have a 7 speed hybrid that is comfortable and fits me perfectly. The setup is factory: 175mm/44t crank/13-34t 7spd

I recently completed my 1st 100 mile urban tour of NYC and quickly found out that the gears left me huffing up long hills at a snails pace... 1st gear was easy but painfully slow. 2nd was only slightly better. Any gear higher than 2nd left my legs screaming. A few of the riders suggested that I get a larger crank, more teeth=more distance traveled per stroke. Others said replacing the rear cassette would help more. Can anyone give an informed opinion? Thanks.

JD