HELP: Awkward when I hear the word 'marriage' or 'wedding'

For some reason whenever my SO brings up the fact that marriage lies in our future I always give the most awkward and unwanted responses 😭 it's not that I want to but I can't help it! Yesterday we were talking about getting a dog one day and buying a house soon and he said but first maybe marriage - my response: "yeah maybe idunno", he then asked me if I want to be a spinster and I said " perhaps" 😓 it sounded like I didn't want to marry him and I'm sure he thought the same 👎 it's not that I don't want to marry him, I really want to marry him so badly - I can't imagine life without him!! We've been together for two years and he's the love of my life, my best friend and my soulmate! But his sister recently got engaged and since then the family keeps asking us when we're going to go down that path and we never know what to say because we're not exactly ready yet (I'm still studying) and it's like everyone is putting so much pressure on us and putting us on the spot when we haven't even discussed it in detail privately 😕 this whole situation is just making it very awkward whenever someone brings up marriage and it's so unnecessary and I DON'T KNOW WHAT TO DO or how to handle the situation 😭