How do I handle the first real "difference" between my SO and I in our relationship?

My SO and I have been together for over a year now and have been living together for about three months.

Our relationship has been effortless, honestly, and we get along like two-peas-in-a-pod. Our likes and dislikes, strengths and weaknesses, happy times and sad times, everything fits together like it was all meant to be. (Just a little side note, I’m 21 and he is 32.) My parents love him, and I love him more than anything.

We are both genuinely happy and in love with one another, have talks of marriage and a family one day. We both believe that this is it.

Now, I was raised to live simply, never have clutter and never have more than I need. This is something that I have always lived by but have recently began to focus on this lifestyle. It’s very important to me. Where as, my SO is more of a clutter-bug, he has “junk” everywhere (I use the word junk lightly, because while it’s junk to me, it’s something to him) We also have a roommate who is the same way. (My SO owns the house)

I have one room in the house that I keep just the way I want it. I do regular purging of unwanted items and things I haven’t used for an extended period of time. It’s my “sanctuary”. While having my own room to keep this way is a means of keeping myself sane, I worry that if we are both set in our ways that things will only fall apart when we have our own house together.

I’m just not sure what to do :( This is the first “red-flag” I have encountered in our relationship and I’m not sure if it’s something I should be concerned about or if I’m being oversensitive and need to chill-out..

Thanks in advance for any and all suggestions and help! If you need any more info on the situation please let me know :)

-LB