My mood is like a rollercoaster!!

I am currently 6w4d with my first pregnancy, 29 yo. I have been treated for anxiety and depression since my teens and have been stable on medication for years (FYI Zoloft, the preferred antidepressant in pregnancy.) I'm wondering if maybe some of you can give me any advice, a positive thought or quote, anything that might help me along because right now I'm having a hard time. 
I had an u/s for dating/viability on Friday and saw the heartbeat. I am SO excited for all these different things, what will my baby look like? Will it be healthy? How will I do this? etc etc. Unfortunately, my mood is as variable as the weather. I woke up fine this morning, and then after laying around for a little I got depressed. I don't feel negatively towards the pregnancy at all so I'm having trouble placing it. Now, I feel much better. In a span of 2 hours! I'm super irritable over things that I wouldn't really give a second chance thought to. I'm pretty sure a portion of what I'm feeling is normal early pregnancy feelings/emotions. Because I've been on meds for so long I'm not really use to this flip-flop my brain is doing! Just looking for some clarity from any of you who have been through this before. Thanks ahead of time, you have no idea how much you can help. 👶🏽