Plant healthy? Too short?

She should be a bit bigger after 3 weeks BUT you mentionned an overwatering and I know thay at that early stage a little over watering can makes her life diffucult so it's cool that she bounced back. So she looks small but she's a survivor so she will now trhive correctly and without issue if you continues to water correctly. From what I can see on the pictures , your soil looks like an "heavy" one , the kind that retains a lot of water ( I may be wrong in my statment ) so I feel like improving your soil could be the solution to avoid watering issue , like mixing it with a bit of perlite or coco fibers/coirs , so if you are planning to transplant in a bigger pot you can try a different mix. Generally the garden shop or growshop soils have enough nutrients for 2 weeks to a mounth depending on the NPK ratio inside of it and the PH is specified on the bag so I am recommending you to take a look at your soil bag to know the PH range ( generally 6.3 or 6.5 but some bags can be 5.5 in the garden shops ) to know if you need to correct the ph or not , in soil the good PH range is between 6 and 7 ph and it's really hard to mess but keeping an eye on it like you'r doing is not bad. The bag will also told you the NPK ratio , for exemple a 5-5-5 npk soil will provide a less nutrients than a 14-15-16 npk and the 2nd will last longer so you'll hae to start to feed later than with the 1st mix.