heater works, but not much air comes out

I put in a new heater core and all of my lines are hooked up correctly because, I have heat and it switches from defrost to vent ect but there isnt much air coming out at all on any setting. My blower motor only works on high but it seems like it should blow harder, and after a while it makes a high pitched whirling noise should i change the blower motor? or just rough it like i did last winter with the heater core bypassed man it was cold..

anyways
any input appreciated

how long will this take to do if i do decide to fix it. I knew the heater core was a bitch to do but if i do recall the blower motor isnt that hard to take out feel free to correct me i guess i will break down and buy one if i do get one will the fan switch and blower resistor come with it?