Janey,
If you are like a lot of anxiety sufferers, including me, when things start to go too well, it makes me feel a little uneasy. I get this feeling like I'd better not get to used to feeling happy, because who knows what might happen. If you have had trauma in the past, and in your childhood especially, feeling happy and good aren't the feelings you associate with home and safety. This sounds sick and twisted, but I think it's true, for me anyway. When things are unstable and I'm struggling it feels like home. I know this feeling of being lost, confused, alone, scared, and angry. As strange as it sounds, these feelings can be comforting because they are more familiar than the positive ones. This can lead to a lot of self sabotage if you don't realize what is going on in your brain.
If you start to feel happy and good your brain thinks "There could be trouble here, better take this happiness down a few notches" With me, I realize that for a lot of my life my focus hasn't been on how to make it great, but how to just barely get by, fly under the radar and make sure my basic needs are met. Not the recipe for a happy life, so I am in the process of trying to change this, but the first step is to realize the force that is fighting this, and this is the force of your survival instinct. Making sure you don't get too happy is your brain's way of protecting you from harm. When you are a kid and you are hurt unexpectedly, you start looking for any sign that it could be about to happen again. You become jumpy and anxious and see trouble everywhere because you are trying to make sense of the situation. That's all I think anxiety is, a perceived threat where there really is none. Anxiety is just you trying to protect the parts of you that have been hurt badly in the past.
I combat this by reminding myself that I am now an adult that can protect myself and I don't have to be on guard against people's behavior or events that might happen. I can trust in myself to be strong enough to deal with whatever comes my way and guarding against happiness actually interferes with my ability to do this. I just have to trust that there will be happy and sad moments in life and that I can be OK in all of them. You have to let yourself have a happy life and this takes work. You are learning a new way to be.
Rachel