Insecurity

I’ve been with my boyfriend for nearly 9 months now. Although I liked him for 2 years before we got together. Anyway, we’re really well suited but the problem is I seem to just go on at him for no reason. Of course I trust him, but I don’t trust other people and he constantly tells me there’s nobody else for him and how he wants us to get a place together when we’re a bit older, get married, etc, etc.. I am so in love with him and cannot face losing him because of my insecurity because it’s making us have arguments that are so pointless and I just need advice on how to get over this because I 100% want to spend the rest of my life with him.