She's Phychologist who has been on her own for 15 years. She is emotionaly fragile and finds her job stressfull, therefore prefers to see me only at the weekends, when her head to clear. How do we progress our relationship to possibly marriage. We are very happy when together.

Sounds like she wants to give you 100% when she can instead of being only half there. Give her time and let her get used to having someone else around, she'll appreciate it a lot more