I don't know if I have advice but I had a similar situation.
I had my first child at 21 and then my second at 23. I was a stay-at-home-mom because we felt it was best for our kids, but we made very little money and I was bored and depressed. I often considered daycare and pursuing a career but we couldn't afford either.
I am now 28, adopting 2 more children, homeschooling and cannot imagine not being with my kids all this time. Though it is challenging at times I absolutely LOVE being a SAHM.
So getting from where I started to where I am took several things. I think the biggest thing was that I asked God to change my heart to give me a love for serving my family as a SAHM and He did. This happened as I became proficient at the practical aspects of being a mom and homemaker, gained a deep appreciation for (and therefore satisfaction in) my role at a philosophical level and as I surrounded myself with support from others moms in similar situations and more experienced moms.
When the kids were older I considered pursuing a higher degree and instead became a labor doula and childbirth educator because it took less time and would allow me the flexibility to still be with them most of the time.
So I'm not saying that you will or should do what I have done, I'm just offering my story as an example of how it can work out and to encourage you to have hope for your situation. With good support, creativity and a positive attitude there's a good chance that if you choose to continue staying with your kids, this will get easier :)