Когда я была маленькой, мама варила манку, а теперь я сама готовлю манную кашу.

Because the speaker is female. In the past tense, Russian verbs agree with gender in the singular:

• я был = I was, said by a male speaker
• я была = I was, said by a female speaker

The same thing appears later in сама: a woman says сама, a man would say сам.

Маленькой is the instrumental singular feminine form of маленькая.

After быть in the past or future, Russian often uses the instrumental for the predicate adjective or noun, especially in expressions like когда я была маленькой. This is a very common, natural way to say when I was little.

A colloquial когда я была маленькая can also be heard, but маленькой is the more standard choice here.

Also, this is not because of когда. The form comes from its relationship with была.

Here it means little / young, not just physically small.

So когда я была маленькой means something like when I was little or when I was a small child. In context, it refers to age, not size.

Russian often leaves out possessive words like мой / моя when the relationship is obvious from context.

So мама варила манку naturally means Mom used to make semolina porridge or my mom used to make it. Adding моя is possible, but it is not necessary here and can sound less natural unless you specifically want emphasis.

Almost, yes.

• манка is the everyday word for semolina
• манная каша is semolina porridge, the full name of the dish

In everyday speech, манка can also refer to the porridge itself, not just the grain. So in this sentence:

• мама варила манку = Mom used to make semolina porridge
• я сама готовлю манную кашу = Now I make semolina porridge myself

The first is shorter and more colloquial; the second is the fuller, more explicit phrase.

Because both phrases are direct objects, so they are in the accusative case.

• манка → манку
• манная каша → манную кашу

The adjective also has to agree with the noun:

• манная → манную
• каша → кашу

So готовлю манную кашу literally uses the accusative form of the whole noun phrase.

The verbs have slightly different meanings:

• варить = to boil, to cook by boiling
• готовить = to prepare, to cook more generally

For porridge, варить is especially natural because you do boil it. Готовить is broader and can mean simply make / cook.

So the sentence shifts focus a bit:

• мама варила манку = Mom used to boil/cook semolina porridge
• я сама готовлю манную кашу = Now I make/cook semolina porridge myself

You could also say я сама варю манную кашу. That would sound natural too.

Because the sentence describes habitual / repeated / general actions, not one completed event.

• мама варила манку = Mom used to make it / would make it
• я сама готовлю манную кашу = Now I make it myself / I cook it myself now

If you used perfective verbs, the meaning would become one completed action:

• мама сварила манку = Mom cooked the semolina porridge
• я приготовила манную кашу = I prepared the semolina porridge

Also, remember that perfective verbs do not have a true present tense meaning. A form like приготовлю means I will prepare, not I prepare.

Сама adds emphasis: myself.

So теперь я сама готовлю манную кашу means now I cook semolina porridge myself. It highlights that the speaker does it personally now, instead of Mom doing it.

It does not necessarily mean alone. If you want to stress alone, context matters, and sometimes одна may be more appropriate.

For a male speaker, it would be сам:

• теперь я сам готовлю манную кашу

А often marks a contrast or change of situation, especially when comparing two facts:

• then vs now
• one person vs another
• one situation vs a different one

That is exactly what is happening here:

• before: Mom cooked it
• now: I cook it myself

So а теперь is very natural. In English it can come out as and now, while now, or but now, depending on context.

If you used но, the contrast would sound stronger, more like a direct contradiction. Here а is the better fit.

Yes, сейчас is possible, but теперь is better here.

• сейчас usually means now, at this moment
• теперь often means now, these days / from now on / in the current situation

Because the sentence contrasts childhood with the present stage of life, теперь is the most natural choice.

So:

• Когда я была маленькой... а теперь... = When I was little... but now...

That contrast in time is exactly what теперь expresses well.

There are two commas for two different reasons.

1. Когда я была маленькой is a subordinate clause, so it is separated by a comma from the main clause:

   • Когда я была маленькой, ...

2. а joins two coordinated clauses, and Russian normally puts a comma before it:

   • ..., мама варила манку, а теперь я сама готовлю манную кашу

So the punctuation is completely regular:

• comma after the when-clause
• comma before а