Anyone Use USPS as a carrier please share

Hello I am currently using my dropshipping companies carrier UPS, I am thinking about switching to USPS, if they will allow me to use that carrier, the rates seem alot cheaper this is what I am currently paying:
Lbs. What they charge me/What I charge my customers:
1 $9.14 /$8.99
2 $9.63 /$9.99
3 $9.84 /$9.99
4 $10.09 /$9.99
5 $10.34 /$9.99
6 $10.67 /$10.99
7 $10.96 /$10.99
They also charge a $2.00 fee for every order (this will remain if i even get my own carrier)
They also charge another $2.50 fee if the order is under $17.00
I charge a $2.00 fee if the order is under $20.00 so Im not lossing $4.50 all together.

Any ideas of what I can do so I am not lossing so much on the shipping, I need to get these shipping prices down, I am currently doing 1 order every week, if I got these shipping prices I would have at least 1 order a day, as soon as they see my shipping prices they run ( I would to) but I am limited to options. and I believe USPS doesnt charge to pick up order either? So I wouldnt have to worry about a $13 fee from fedex if i went with them a week

Okay I have decided to go with FedEx. Now I need some help with making a decision. Fedex prices are about $2 or mroe cheaper on every order then what I get now. How can I work this $2.00 fee? and then the $2.50 fee if the order is under $17 any ideas so Im not lossing the money.

You could test for the $order->info['total'] amount and then apply the extra charge you want to the $cost ...