Pregnant with an infertile friend

Kerri
I am currently pregnant and my coworker and friend is trying to concieve with little success. We have been talking about ttc together so I knew I wouldn't be able to hide it. I told her at about 6 weeks, privately and was not upset when she quickly told me congratulations and then excused herself. I know she is happy for me but also upset she is having a hard time. 
I feel awkward bringing up my pregnancy and don't mention it until she brings it up or asks a question. We see each other every day and I don't want it to strain our relationship. Any tips on how I can make this as painless for her as possible?