Issues with usb port

Hello everyone, i will explain you my issues on my N5. Firstly, sorry for my bad english. :silly:

I think my usb port is broken, but not completely : for charging my phone, i need to hold my cable on a good position. You will said "yes it is broken !" However, when i connect a OTG cable, it works like a charm (i can read and write my usb key). And now, you will said "change your usb cable!". I did. I tried with 3 differents cable, no success :eek:
Finally, when i connect my phone on my computer (and 2 others computer) with these 3 differents cable, nothing happened.

I am running on M Developper Preview 2, but i really dont think that is a software problem. I have seen that i can change this port for 20€ (yeah i am french :p). I have already changed my battery two weeks ago. Do you think i need to change my usb port?

Thanks.