indifferent feelings about pregnancy

We are pregnant with our 4th baby! I'm only a little over 7 weeks along, and I can't shake this feeling of not being super excited. I just feel like "ok I'm pregnant". We have three sons and I don't want to tell anyone I'm pregnant because I'm trying to avoid "Oh I bet it's another boy!" and "I hope you get your girl!"  I honestly probably won't say anything until I know what I'm having. I'm finding it really hard to be excited and it's bothering me so much because this baby is definitely a blessing. No one knows other than a few friends and no family knows at all. I'm not really ready for their opinions or judgements on how soon I got pregnant after my last son (he's 15 months). I just don't know how to feel. I just want my baby to grow and be happy and healthy. I want so badly to be excited about buying baby things but I just can't bring myself to look at any baby things. I just need some encouragement!