But, what I'm getting is very small & my plants are not showing any growth.
Pictures always help.....
Organic matter added to the clay will help... Winter cover crop like rye or oats will help break up the clay.. be sure to till it in, in the spring, as green manure....
I'm in a similar situation, having moved to here last August. I dug a rain garden basin to get water away from the house and the soil there is awful, clay and gravel exactly like you'd see in compacted roadbed fill. The rate of "infiltration" (soaking in) is extremely slow.
This neighborhood was developed around 1955. Someone told me the practice back then (and maybe now) was to first scrape off the topsoil and sell it. If I go about 2 miles west of here I'm in farmland and the soil is BLACK like a prairie.
I hired a tiller to cut a new 20X15 garden bed and mix in manure and compost. That garden is a riot of vegetables, from potatoes to peas to peppers to popcorn. I want Linda's grandson to see onions and potatoes coming out of the soil.
BTW ordinary popcorn from the grocery shelf can be viable. I planted two rows before the squirrels got wise and raided it. So it is that I have the lone corn plant growing among the peppers.