With trauma therapy, things almost always get worse before they get better. I would really encourage you to stick with it.
Imagine your emotions come out through a funnel. In an individual without PTSD the emotions flow freely. Happiness comes through, maybe sadness, confusion, etc.—whatever emotion comes, is allowed out. PTSD is essentially a stopper in the funnel. It happens when you can't safely process the emotions at the time so you "put a stopper in the funnel." Imagine you're in a car accident. Normally you might feel afraid, scared, mad, confused, sad, etc. etc... but in order to stay alive you might have to call 911. So you put those emotions "on hold" until you've done the things you need to do. You stay calm and tell the operator where you are and what happened. Then, normally, you let them out later—maybe in the hospital or when you get home. In this case (what usually happens) the emotions are let out and you don't develop PTSD. Then you remove the stopper in the funnel and you get all the afraid, scared, mad, confused, sad feelings that were pent up... as well as any that got stuck behind it. Maybe someone brought you flowers at the hospital but you couldn't really feel grateful because those emotions were "stuck" in the funnel. But when you get home you just cry. Why? Coming home isn't sad. You're probably happy to be home. But you have all those pent up emotions that didn't come out earlier, that still need to come out.
PTSD happens when it isn't safe to let out the emotions later, either. So let's say you get home after the accident and you start to cry and your parent starts yelling at you ("Why are you crying!?" or maybe "be a man!" if that applies. Or maybe THEY start crying and you feel like you have to take care of them and you can't feel your feelings). So you KEEP the stopper in the funnel. If you keep it in for more than 30 days—that's PTSD (or CPTSD. PTSD is single-serve, like a car crash. CPTSD is ongoing, like an abusive parent). And you probably struggle to really let yourself feel sadness for the rest of your life, or until the PTSD is treated. And you probably feel pretty numb about other things, too, because there's a stopper in your funnel. Happiness can't really get out, for instance. And your body will try and find all sorts of ways to get the emotions out—headaches, fatigue, dissociation, nightmares, negative beliefs about the self ("I'm bad"), etc. Our bodies are not made to hold that many things in the funnel for that long.
Then when you finally DO get treated for PTSD, all those emotions still need to come out. Not only the ones from the original trauma but all the ones that came after those that couldn't get past the stopper. Depending on how long ago the PTSD was this could be years or decades of stuff pent up. And it sucks. It totally, really, absolutely sucks, feeling all that pent up stuff. And it can take multiple sessions, maybe even weeks or months—again depending on the trauma, how long it went on, and how long ago it was.
Not only those feelings but feelings about those feelings. Maybe sadness that you missed out on what happiness really feels like. Maybe anger at your parents for not letting you cry. Maybe anxiety because the last time you cried you got yelled out. It all has to come out. For me, personally, I've felt a lot of guilt at all the relationships I sabotaged because I wasn't happy in them... even though they were really healthy relationships, my inability to feel happiness aside.
So it all really usually sucks quite a bit because you've never felt a lot of those those and you've certainly never felt them that intensely.
So yea... things are gonna get worse for a while. But then they will (usually) get better. If there is one thing we know, it's that therapy works. There's tons of evidence behind it. Provided, of course, your therapist is using evidence-based practices (which EMDR is) and you have a good relationship with them. Those are the two sort of caveats.
I would ask your therapist what to do with your feelings in-between sessions. There are various exercises you can do to help you manage what comes out in session. One of the early stages of EMDR is called "resourcing" and goes over this.
Hope that helped. Obviously it is 100% your choice but if you do want to resolve whatever's going on then things getting worse before they get better is almost certainly part of that.
Also, unless it's a single-serve trauma, I'd look into getting a therapist covered by your insurance. Paying $150/session for treating CPTSD, which can take years, will get very expensive very quickly. If it was something like a car crash that can probably be done in less than 10 sessions.