The Nikon D3400 is actually a pretty nice camera, you likely don't need to upgrade. You might, but you might not. You need to reconsider things if you haven't though because the camera body isn't always what needs an upgrade, despite what gearfags will claim. You don't need 15 FPS burst firing or anything right? Or higher res video? If not, then you'll probably be fine with the D3400 for a long time.
What lens are you using?
You might find it better to invest in a fancy lens, because many of the issues with budget DSLRs are actually bullshit. Like they're not real. People usually mistake their poor photo quality to be the fault of the camera when it's the lens to blame, because they're noobs and never bother to use anything but the kit lens. One key element to a lens is the aperture. Wide aperture lenses let more light in, but have "bokeh". This can lead to the smooth backgrounds/lighting you might be looking for but compared to kit lenses a prime lens can let in up to like 4x more light which means you can drop to 100 ISO vs 400 or whatever for an indoor shot or for a better example let you take a decent shot at just 400 ISO vs needing 1600 or higher or 1600 vs 6400. That's a significant difference.
Also if you haven't already then you should learn to process RAWs. A RAW from a D3400 will produce a better image than a JPEG from the next tier.
If you're unsatisfied with processed RAWs from well lit scenes taken with a good lens and good composition and base ISO with a tripod/good exposure then you'll want to upgrade but don't just buy a new body without seeing what yours is capable of.