My main concern with your sentence is that is too wordy. (= too long, has too many words). Consider the following shorter version.
I am determined to become more skilled (in this field), in order to better help people in my still-developing country enjoy longer, healthier and wealthier lives.
I prefer 'more skilled' over "better skilled".
If people already know what field you mean, you can omit "in this field".
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