I live 3 nights a week at my boyfriends place and 4 nights a week with my parents but I just don't feel settled at all. I feel like I am living out of bags and it is really frustrating me.
Your sense of security and safety comes from inside you and is not necessarily as a result of where you are residing.
I do hear that you would prefer to be living in one place and feeling more settled - with your belongings all around you - and that is something you are working towards.
The only way to 'feel more settled and less stressed' in this present situation is to accept it for what it is... and that it's 'for the time being' and not permanent.
You have a choice about what you feel as well as where you live - and your choices can change.
For now you are in transition stage. It's important to focus upon building a solid foundation in your relationship - which may then develop into you living together full time if that is what you both want and decide.
In the meantime focus upon the positives of having some time apart, and the freedoms this brings you - you may miss this when you are living with your boyfriend 24/7 :-)