אני לא סומך על הידיים שלי כשאני מחזיק יותר מדי דברים, כי אז אני לפעמים מאבד משהו חשוב.

Because the verb לסמוך meaning to rely on / trust normally takes the preposition על.

• אני סומך עליך = I trust you / I rely on you
• אני לא סומך על הידיים שלי = I don’t trust my hands

This is just the standard verb pattern in Hebrew, even though in English we do not always use on in the same way.

In modern Hebrew, possession is often expressed with:

• a noun, often with ה־
• plus a possessive word like שלי, שלך, שלו, etc.

So:

• הידיים שלי = my hands
• literally something like the hands of mine

This is a very normal way to say possession in everyday Hebrew.

ידיים is the form for hands, from יד = hand.

The ending ־יים is historically associated with the dual, especially for things that come in pairs, like body parts:

• יד = hand → ידיים = hands
• רגל = leg → רגליים = legs
• עין = eye → עיניים = eyes

In modern Hebrew, learners usually just memorize these as common plural forms for paired things.

Hebrew often includes the pronoun in the present tense because the present-tense verb form does not clearly show person.

For example, מחזיק can mean:

• I hold
• you hold
• he holds

So כשאני מחזיק clearly means when I am holding / when I hold. Without אני, the sentence would be less clear unless the context already made the subject obvious.

Because Hebrew present tense is commonly used for:

• actions happening now
• habitual actions
• general truths

So כשאני מחזיק יותר מדי דברים means when I’m holding too many things or when I hold too many things, depending on context.

Likewise, אני לפעמים מאבד means I sometimes lose. Hebrew does not need a separate form like English I do lose or I tend to lose here.

The present-tense verbs would change to feminine singular:

• אני לא סומכת על הידיים שלי...
• כשאני מחזיקה...
• אני לפעמים מאבדת...

So the sentence would become:

אני לא סומכת על הידיים שלי כשאני מחזיקה יותר מדי דברים, כי אז אני לפעמים מאבדת משהו חשוב.

The pronoun אני stays the same; the verb forms change.

יותר מדי means too much or too many.

Here it comes before the noun phrase it modifies:

• יותר מדי דברים = too many things

Other examples:

• יותר מדי מים = too much water
• יותר מדי אנשים = too many people

So in this sentence, it describes the quantity of things being held.

כי means because, and אז means then / at that point.

Together, כי אז gives the idea of:

• because then...
• because in that situation...

So it links the cause and the result more clearly:

• I don’t trust my hands when I’m carrying too many things,
• because then I sometimes lose something important.

It sounds natural and helps show the consequence.

Yes, Hebrew adverb placement is somewhat flexible. לפעמים means sometimes, and here it appears before the verb:

• אני לפעמים מאבד משהו חשוב

That is very natural. You may also hear:

• לפעמים אני מאבד משהו חשוב

Both are acceptable, though the emphasis can shift slightly depending on word order.

Because את is used before a definite direct object, and משהו חשוב is indefinite.

Compare:

• אני מאבד משהו חשוב = I lose something important
• אני מאבד את הדבר החשוב = I lose the important thing

Since משהו means something, it is not definite, so את is not used.

For losing or misplacing an object, לאבד / מאבד is the correct verb.

• לאבד מפתחות = to lose keys
• לאבד משהו חשוב = to lose something important

להפסיד / מפסיד usually means to lose in the sense of:

• losing a game
• missing an opportunity
• suffering a loss

So in this sentence, מאבד is the natural choice because the speaker is talking about physically losing an item.