"Aceasta" without the smiley ă is used after the noun. Before the noun is "această". You might be confusing this feminine form with the masculine forms: "acest" before the noun, and "acesta" after the noun. Hope that helps :)
I wonder how mici compares to small, little and tiny and whether any Romanians might comment on this - might they say foarte mici for tiny? DL not accepting little here either though for me, an Englishman, it is a good English option.