Fun fact, I have porridge for breakfast every day. I have porridge for breakfast every day.

I've gotten used to it since my boyfriend and I started to live together. I've gotten used to it since my boyfriend and I started to live together.

I've gotten used to eating it since my boyfriend and I started to liveliving together. I've gotten used to eating it since my boyfriend and I started living together.

Since it's an ongoing action, the -ing forms of the verb will be better here.

Before this I had a tea and some sweet things like cookies for breakfast. Before this I had tea and some sweet things like cookies for breakfast.

Before this I had aI used to drink tea and eat some sweet things like cookies for breakfast. I used to drink tea and eat some sweet things like cookies for breakfast.

Is this referring to before you started living together? If so, you might say "Before we started living together, I used to..." or "When I lived alone, I used to..." to clarify the timing.

We have been eating cereal in the morning for approximately one year. We have been eating cereal in the morning for approximately one year.

This sentence uses a perfect tense "we have been."

We haved been eating cereal in the morning for approximately one year year or so. We had been eating cereal in the morning for a year or so.

For an informal work, "a year or so" sounds more appropriate than "approximately one year", which carries a formal feel.

Then we switched to buckwheat porridge. Then we switched to buckwheat porridge.

This sentence uses simple past tense "we switched"

ThenAfter that, we switched to buckwheat porridge. After that, we switched to buckwheat porridge.

We add some fruits and toppings to the dish so we've not got tired of it. We add some fruits and toppings to the dish so we've not got tired of it.

This sentence uses the present tense "we add"

We add some fruits and toppings to the dish so we've no don't goet tired of it. We add some fruits and toppings to the dish so we don't get tired of it.

We add some fruits and other toppings to the dish so we've noour porridge for variety so we won't goet tired of it.eating it every day. We add fruit and other toppings to our porridge for variety so we won't get tired of eating it every day.

Just a little more explanation needed to make it sound more natural.

Sometimes we cook something else,; for example, an omelette or pancakes. Sometimes we cook something else; for example, an omelette or pancakes.

Sometimes we will cook something else, for example, like an omelette or some pancakes. Sometimes we will cook something else like an omelette or some pancakes.

But we cook the porridge more often. But we cook porridge more often.

But we almost always end up cooking the porridge more often. But we almost always end up cooking the porridge.

This phrasing gives the idea that, while you like other things, you know that the porridge is the constant part of the meal.

There's one more thing I usually eat, - it's chocolate. There's one more thing I usually eat - it's chocolate.

Or, to write without a sentence inversion, you could say "Another thing I eat is chocolate."

There's one more thing I usually eat, it's chocolate.I also love to eat chocolate in the morning. I also love to eat chocolate in the morning.

I think it's a bad day if I don't get anmy chocolate., it's going to be a bad day. If I don't get my chocolate, it's going to be a bad day.

More natural phrasing for both these last sentences.