Lisa, i'm sorry to hear that you're going through this.
I can sympathise with you in that when you're TTC its REALLY hard to see pregnant women, or hear about pregnancies, and its virtually impossible to be happy for them.
Give yourself some 'you' time, and take Wobbles suggestion about what to say to your friend...you don't have to go to the hospital - there is no way that I could do that - it would honestly be torture, so don't put yourself through that. If she is a real friend, she will understand.
I know that its really scary at the thought of getting tests done (just done that) but honestly, it is better that you find out sooner rather than later if there is something wrong. Its only natural to expect the worst, but look at all the technologly and meds out in the world today - clomid, GIFT, ZIFT, IVF, the list does go on. If there is a problem, the chances of it being one that can still enable you to get pregnant with assistance is really high!
Feel free to PM me ANYTIME for a chat or vent or anything. I hope you're feeling better soon
