У меня в ботинке сбилась стелька, поэтому идти неудобно.

Yes, У меня is the normal Russian way to express possession in many contexts.

Literally, У меня means by me / at me, but in natural English it often corresponds to I have.

So:

• У меня в ботинке сбилась стелька
  literally: At me, in the boot, an insole got displaced
• natural English: The insole in my boot has slipped out of place

Russian often avoids using a direct equivalent of my when possession is already clear from у меня.

Because Russian often leaves out possessive words like my when the owner is already obvious.

Here, У меня already tells us whose boot it is, so в ботинке is enough.

Compare:

• У меня болит рука. = My arm hurts.
• У меня в ботинке сбилась стелька. = The insole in my boot has shifted.

You could say в моём ботинке, but it would usually sound more emphatic or specific, not neutral.

Because it follows the preposition в in the meaning in.

The basic form is ботинок. After в meaning location, it becomes:

• в ботинке = in the boot / shoe

So:

• ботинок → dictionary form
• в ботинке → location inside the shoe

This is a standard use of the prepositional case after в when talking about where something is.

Here сбилась means something like:

• got bunched up
• slipped out of place
• shifted
• became misaligned

It comes from сбиться. In this sentence, the idea is that the insole is no longer lying flat where it should be.

So стелька сбилась is a very natural way to say that the insole inside the shoe has moved and is now uncomfortable.

Because the verb agrees with стелька, which is a feminine noun.

• стелька = feminine
• past tense feminine form = сбилась

Compare:

• шнурок сбился — if the subject were masculine
• что-то сбилось — if the subject were neuter
• стелька сбилась — feminine

So the ending -ась / -лась / -илась here shows feminine past tense.

Because стелька is the subject of the verb сбилась.

The sentence is not saying that someone did something to the insole. It is saying that the insole itself shifted / got displaced.

So:

• стелька = the thing that changed position
• therefore it stays in the nominative case

This is different from a sentence like:

• Я поправил стельку. = I adjusted the insole.

There, стельку is accusative because it is the object.

Because идти refers to walking as a concrete action in progress or in one direction, while ходить is usually more general, repeated, or habitual.

Here the speaker means:

• walking right now / continuing to walk is uncomfortable

So идти неудобно fits well.

Compare:

• идти неудобно = it is uncomfortable to keep walking right now
• ходить неудобно = it is uncomfortable to walk in general / habitually

Both can exist in some contexts, but идти is the more natural choice for this immediate situation.

Because the meaning is not I walk awkwardly. It is it is uncomfortable to walk.

These are different ideas:

• Я неудобно иду would sound odd and unnatural here.
• Идти неудобно is an impersonal construction meaning walking is uncomfortable or it’s uncomfortable to walk.

Russian often uses this pattern:

• мне трудно понять = it’s hard for me to understand
• здесь приятно сидеть = it’s pleasant to sit here
• идти неудобно = it’s uncomfortable to walk

So the focus is on the experience, not on the manner of movement.

Here неудобно is not an adjective describing a noun. It is a predicative adverb / category-of-state word meaning:

• uncomfortable
• inconvenient
• awkward

In this sentence it functions as the main predicate in an impersonal clause:

• идти неудобно = it is uncomfortable to walk

Compare:

• неудобный ботинок = an uncomfortable shoe
  Here неудобный is an adjective describing ботинок.
• в ботинке неудобно = it’s uncomfortable in the shoe
  Here неудобно expresses a state.

Поэтому means therefore, so, or that’s why.

It connects cause and result:

• У меня в ботинке сбилась стелька = cause
• поэтому идти неудобно = result

So the full logic is:

• The insole in my boot has shifted, so walking is uncomfortable.

It is a very common connector in Russian for expressing consequence.

Yes. Russian word order is flexible, and different orders change emphasis more than basic meaning.

The original sentence:

• У меня в ботинке сбилась стелька, поэтому идти неудобно.

Possible variations include:

• В ботинке у меня сбилась стелька, поэтому идти неудобно.
• Стелька у меня в ботинке сбилась, поэтому идти неудобно.

These all express roughly the same core meaning, but the original version sounds natural and neutral.

Russian often places context-setting information first:

• У меня — whose situation this is
• в ботинке — where it is
• then the main event: сбилась стелька

It often means a sturdy shoe or boot, depending on context. English translations vary.

So в ботинке could be understood as:

• in my boot
• in my shoe

The exact footwear type is less important here than the fact that there is an insole inside it.

Yes, it sounds natural.

A native speaker might also say similar versions such as:

• У меня в ботинке стелька сбилась.
• В ботинке сбилась стелька, идти неудобно.
• У меня стелька в ботинке сбилась, поэтому неудобно идти.

All of these are plausible. The original sentence is perfectly normal and idiomatic.