No baby yet and sad

Jennifer
Hi, I am new to the group, however been ttc for about 4 years. I have had 1 pregnancy (after about 3 years of trying) and he is now 4.5 years old. I am trying for baby #2 and so far no luck. I am sad and depressed every time my period comes. I am thankful for my son,  so thankful, but I would love another child. My son asks for "a baby" and so sad that it is not happening. I feel at war with myself always saying this is the last month, or I am almost ready to give up but I don't think I really am. Any advice, suggestions or just support?  Thanks