Need some advice...

My best friend has been TTC for 7 yrs with no luck. I started TTC in January, got pregnant that month but had a miscarriage in February. We weren't supposed to TTC again until April but even though I avoided my fertile days in March I somehow got pregnant again. I am only 5 weeks right now but I don't know how to tell her. She knows about my miscarriage but I told her after it happened. I don't know if I should wait till we are further along or if I should tell her now, seems like there won't ever be a good time to tell her. I mean she is my best friend. I know she will be happy and excited for us but she is also going to be sad and I understand that and my heart hurts for her. Just don't think she should find out when we are surrounded by others. I would appreciate advice from anyone that has been TTC for a couple of years and could tell me how to go about it.