Secondary infertility

I am 34 and have a 2 year old, who I am so grateful for. I have been trying for 10 months for my second. I'm so frustrated and feel so guilty about not feeling content with my family. My doctor wants me to wait until March to see if there is any underlying issues. I get so sad seeing siblings playing and wishing that for my child. I just got my period again and am feeling so down. I feel that already havinga kid means that I don't get to be sad. It has been so hard finding any support. Any ideas of how to cope? Or what next steps might end up being?