I just don't know how to feel...

About my 3rd pregnancy in 5 months. I only got my bfp Wednesday and I already feel sad,depressed and anxious at the thought of losing this one too. I'm not excited and I hate that I'm so discouraged. I'm just expecting to start bleeding every moment of the day. I'm not worried really. Just expecting it to happen. How can I get my heart into this pregnancy? My last pregnancy I was SO DAMN EXCITED when I lost it I was beyond devastated. I know I need to just be positive. I'm usually the most positive one in any situation but this time I can't seem to find it in myself to be happy.