I think op, at 23 you have LOADS of time to be thinking about expanding your family. I only had my first at 35! I understand feeling broody totally and that can be quite overwhelming, but you need to think about this logically. If you need to be a single parent to 3 children that's going to massively impact the life you can provide for them. I'm a single mother to one ds and I would LOVE to have more, but I know there is a limit to what I can provide financially for ds. I want to be able to accommodate school trips, hobbies, things he wants that his friends will have, holidays, days out as a family and to have money aside to help set him up with things like a car or a house or getting married that will be even more expensive by the time it comes around for him to try and do it. I work full time and I earn a good wage but it's still really tight.
Obviously everyone has to weigh up their priorities for parenting within their budget, but I want ds to grow up secure and with stability and I know if I had more children that would just get harder with each child.
EUPD can also make it difficult to sustain a solid support network and to maintain healthy relationships. You need to try and get to a place where you are the most stable in yourself before you add more responsibility and demand into your life. Because while babies are wonderful, they are super intense as well. And as a single parent you have to have a decent support network around you to help you manage. I think op you need to really think about what a child needs from their mother and if you can realistically provide that for 3 children all at the same time.
The breakdown of my family was by stbxhs doing but that was still a trauma and a big loss for ds even though he was really small at the time. I cannot imagine being willing to put a child through that just to satisfy my own desire to have a baby. Being a mother (especially a single mother) in a big part is about sacrifice and putting your children before yourself and your own wants and needs so you're setting them up for the best life they can have.
I agree with others who recommend you channel your broodiness into being the best mum you can be for your existing children and use this time to really invest in yourself, your wellbeing and managing your own mental health. Your existing kids need the best possible version of you, not a sibling and a mum who's spread herself too thin and is struggling.