昨天的購物

1. If the possession is indicating people, "的" is usually omitted. For example, 我妈妈，我女儿，我同事。

2. Any action happened in the past, there should be a "了“ after the verb, unless the sentence is negative. For example,

我今天吃了饭。

我今天没吃饭。

3. “兒童” is a a very formal word usually appears in news/articles/etc.

4. "Verb. + 得 + adjective" is usually used to describe an action:

For example, 玩得很开心, 吃得很健康.

昨天的購物

in many occasions,  you should add a measure word before a item，the measure word for 车 is 辆。

I think you want to express the bicycle is not for me, but for my daughter . If you want to emphasis something happened （like time, place, person, purpose, method）in the past,  you can use this pattern 是……的。e.g. 我是去年来北京的。（emphasis time）  他是在学校学的中文。（emphasis place）。

Here 這辆车不是给我买的，是给我女兒买的。 是……的 pattern emphasis the person who receive the action。

Cause all the other sentences  are oral language  style,  you can replace 儿童 with 孩子 which is more suitable