Best for her is to get her a friend!
Most piggies warm up to their humans through food. Offer her bits of veggies to entice her to approach your hand and take the veggies from you. Show her the hand isn’t scary but brings yummy things.
When on your lap, some piggies prefer to have something to cover them, some don’t mind being in the open, but food is always good.
Always keep in mind that a guinea pig is a prey animal and their instinct is to run and hide, this is no reflection on you or your relationship with the piggie. It takes time for them to get used to you and some will always keep running when you try and pick them up even though they may like being on your lap after the scary pick up.