What should I do?

it's not showing symptoms. Not falling over. At this point, the seed is still powering its own growth with no need for nutes elsewhere (10-14days from sprout). Your soil likely has nutes for another X weeks depending on how "hot" the soil is. So, you want to ease into fertililzing to offset what is lost form soil, then pretty much supplementing everything needed after that. Patience, grasshopper. I wouldn't call it "short." It;s about right for a seedling with leaves 'that' size. The initial growth is slow... you'll see or can see little nubs of next set of leaves. Until you get some big solar panels (leaves) it will be slow moving growth, but it speeds up exponentially after that (to a point*). What i do see is a big pot for a tiny plant. This can make irrigation difficult for the next week or two until the plant prolly gets 3rd or 4th set of full grown leaves. So, while it is tiny, water a smaller diameter around the plant and make sure it runs out bottom -- want entire column to get wet. A diameter a bit larger than canopy of plant. Err on side of being safe and slightly bigger diameter than you think. wait for top 1" to dry, and repeat with slightly larger circle until entire pot is getting wet and not staying wet for 8-10+ days at a time. This will allow a better wet-dry cycle to occur - you may still have 5-7 days between irrigation early on with seedlings But will soon be every 3-4 days or less.. Helps avoid damping off, pests, mold growth etc... trains roots to grow deep instead of supeficially. As plant grows, do entire pot that way.. wait for top 1" to dry and repeat process. I have to contradict somethign below.. 6.7 pH is fine in soil... prolly better oscillating around 6.5. A soil medium is better in this range due to improved availability of nitrogen (there are differences between optimal pH of soilless/hydro and soil). Use a bit more perlite or vermiculite to improve drainage (hydroton, whatever floats your boat here). Vermiculite has added benefit of providing a useable silicon, unlike the other options. I've used both perlite and vermiculite and .. i must admit i am starting to prefer perlite (contains silica, but not soluble/available to plant). a 50/50 is good goal with soil or peat-based substrate. 70/30 if you go to coco. It will help avoid overwatering - virtually impossible unless you just douse it for 15minutes straight. Still wait for that top 1" to dry, of course, before repeating irrigation.

Everything looks good to me. It can feel like she is not doing much, But what your not seeing is her establishing a root system. Just keep an eye on how much you water. You wait to let the soil dry out to 1" below the surface. Roots need oxygen and will rot if they sit in soggy soil. At this stage you want to change as little as possible. Giving a seed to much attention can cause stress and stunt her growth. Let her grow. Happy Growing.