Low pressure

I live in a 2000 SF one story, two bath home with 3/4" copper trunk line and 1/2" service lines. I have a well 130' from my home with one and quarter inch line to my home, the pressure is set at the well to range from 45 psi to 69 psi.
I have the common problem in my home of using two services at once. If showering and a toilet is flushed, the dishwasher or washing machine is in use,it makes showering almost impossible.
I am currently researching using a Grundfos MQ3 series pump added in my trunk line under my house.
I'm sure this subject has been discussed previously on this site but I would like advice and comments from folks with experience using this system.
Thanks in advance,
Frank

We're all UK based, Frank, so don't see wells much.
Is it both H and C which are similarly affected? If it's only the hot, there could be a restriction in whatever does hw for you.
On the face of it the pipe sizes sound reasonable, unless they're full of rust/dirt etc.

Since I've begun my research It's becomming obivious that my plumbing configuration is probably the problem. My trunk line has T's to my serivices and water is going to take the path of least resistance. Having read about the water manafold that is being used in new homes seems the answer to my problems, the manafold allows for a more uniform distribution of the water.
I pretty certain I don't have any obstructions in my lines, I built my home in 1976 and things really haven't changed with regard to performance.
Thanks