Hi! If you look at my post history you'll see I posted something almost identical a couple of months ago about anxieties relating to home ownership. I had some really good support on that thread.
I'm really sorry you're feeling like this! If you look at my thread, there was loads of good advice from mumsnetters. I was feeling almost suicidal about the house worrying it was structurally unsound and that I'd made a terrible mistake. Two months on I am sat in my own master bedroom, watching TV, feeling totally relaxed and at peace. You will feel the same too, I promise.
Your house feels cold and uninviting because you haven't been there long. It will take you a long time to get it exactly how you want it and you're probably comparing it to new build show room houses and getting yourself down because of that.
Light some candles, get some blankets from Dunelm or similar. Write a list of all the things you would like to do to the house to make it feel nicer. Slowly and gradually you can tick things off that list. Even tiny things like replacing bulbs with warm white instead of harsh yellow can make the place feel a lot more homey.
I don't have much advice, but going to the doctors for my anxiety and getting on meds really helped. I was crying and having panic attacks every time I moved through the house thinking it was going to fall apart and worrying about the mistake I thought I'd made. So although I don't have much concrete advice, you won't feel like this forever and in time you will adore your home and all its quirks and character.
The first time buyer anxiety is so so real and it's such a big commitment. But you have done so well to get on the property market and in time you will love the home, and if not, you will definitely be able to sell, so please try not to worry about the house being unsellable. Some advice I had was that very few houses are truly unsellable and your one won't be one of them!