Loves, it could be so many things that are bringing you down or just a combination of many things. You missing Noah, being back home, knowing you will be leaving again, being around your daughters but to know the time is limited, trying to make everyone happy, or not succeeding and they are putting to much pressure on you, grandbaby is coming but you will leave soon after.... all those things could just be going round and round in your head... of course you would feel sad. Try to just live for today and put everything and I mean everything on the back burner.