It’s always a bit of a pain to get adjusted to a new medication, I’m having the same issue and it’s not the first time I’ve been through this process. I think that in my case I give the medication about two weeks to determine if it will help me, I know that they usually take about 4 to 6 weeks but not for everyone, I can tell by the first week of it’s working for me or not. I don’t know if this is your first time taking antidepressants or not so a lot depends on your experience with them and being able to determine whether it’s helping you, feeling very low is a side effect and it should settle down but I think it’s a good idea to go back to your doctor and discuss what you’re experiencing, they might change your medication or increase your dose, either way try not to get discouraged because it may take time to figure things out, best wishes for you and I hope you have a happy new year.