Weak Water Pressure in New Attic Bathroom

I just installed a new bathroom in my 3rd story attic (about 30 fee above ground) and have very week water pressure. I haven't measured the pressure, but its flowing at just under 1gpm. The bathroom water supply was originally connected to the hot/cold pipes from 2nd floor bathroom (just below), until I ran new plumbing all the way up from the basement to try and solve the pressure problem (this didn't change anything)

Additional details:
-Pressure in rest of house is fine, including 2nd floors
-house is all half inch copper piping except the new bathroom which is 1/2 pex
-3/4 pipe from city (Saco, Me)
-new 1//2 pex plumbing coming from the basement serving only the new attic bathroom.
-attic bathroom has double vanity, shower, toilet - pressure is equally low in each.
-Hot/cold have equally low pressure in attic bathroom

So, the question is, what are my options to solve problem?

30 feet of height will cause a pressure loss of 13 PSI. Measure the pressure at a hosebib on the ground floor. 40 PSI at the fixture is generally sufficient, you can get by with 30 but you won't like the pressure. So you will ideally have 53 PSI or more at the ground level.

to add to a great answer. you also cut down the volume of water by installing under sized piping
minimum size to that bathroom is 3/4" . here is a rule of thumb for upc code

1/2" to 1 fixture only, 3/4 to 2 fixtures then tee off with 1/2" to the last

phishfood said:

30 feet of height will cause a pressure loss of 13 PSI. Measure the pressure at a hosebib on the ground floor. 40 PSI at the fixture is generally sufficient, you can get by with 30 but you won't like the pressure. So you will ideally have 53 PSI or more at the ground level.

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Thanks for the advice and here's the result.

I just measured the pressure at the garden hose connection and it was 60psi.
I also measure it at the 3rd floor bathroom and it was 50 psi.

I guess this mean I don't actually have a pressure issue. What could cause such a low volume of water to flow?

Have you measure the pressure at the 3rd floor with the fixtures turned on?

As long as you don't run multiple fixtures at once, the 1/2" SHOULD be able to supply the demand. I would have ran 3/4" cold, but stayed with 1/2" hot.

Have you made sure that the aerators and screens in the showerhead and faucet are clean?