Hi there! I also have a teeny weeny tank! I bought it because the cost of messing up & killing all my plants wouldn't be so bad! And I like the 'white ground' you have but as other members have said - I think plants may find it harder to root. Some people cap their substrate with a light colour sand ... This might work - though as a tank matures the white is more likely to look 'dirty' and harder to maintain I think!
Stocking options are tricky but you could try 8/10 chilli rasbora (chilly raspberries my daughter calls them)
Or if you wanted a single fish you could try a pygmy dwarf puffer, sometimes called a 'pea' puffer. Or a scarlet badis - shy but apparently a great fish if kept alone or sparkling gourami....
Nice options to consider! I love puffers... Chilli Raspberries look nice as well!