Anxiety in relationships

You know I thought i was doing well, since being in this new relationship I feel my anxiety problem had went away
,Well not completely away because I have had a few minor ones, but I think all it's done is shifted into relationship anxiety.
I've never been with someone and felt this nausea I get when I overthink things and I bloody hate it ..I will be the one to drive him away!  Is what I keep saying to myself , trying to pin point the reason for feeling this way, I'm not sure.
Maybe it could be that I'm now coming up for 31 and no where near where I was wanting to be in life , married and with kids ...Maybe I'm just scared of being in a relationship again because to be honest I'm scared of possibly loosing many years of my life  again and still might be no where near close to being a wife and mother, it's scary it really is then I think about other things ...Does he like me as much as I like him  , will he leave me, does he even like the things I like  everything with us is perfect except I have to deal with all this in my head and I wanna tear my hair out!