Due to the word order of the Korean language, all sentences (unless they're incomplete^^) will end in either an action or descriptive verb. This means, most sentences will end in 요 or 다 (unless they're very informal). In addition, providing translations of what you intend to say will help both correctors and other learners.
1) 제가 의사가 되고싶은
-> 저는 의사가 되고 싶어요.
"I want to become a doctor."
*싶은 is the noun-modifying form of 싶다 (to want). It won't end a sentence. It will go in front of a noun, and then a verb will come after that to finish the sentence.
**The emphasis is on what you want to become (저는 의사가...)
2)그러나 내가도 공부 좀 독일어하고 스페인어
->그리고 (저는) 독일어하고 스페인어를 (조금) 공부하고 싶어요.
"Also, I want to study (a little bit of) German and Spanish.
*저는 can be omitted since we already know that you are speaking about yourself and your desires (that you are the topic).
**The sentence needs to end in a verb ^^ V+고 싶다 means "to want to V", where V stands for verb. (ex. 먹고 싶어요 - (I) want(s) to eat)
***좀 is usually used to soften a sentence, such as when making a request or saying please. 조금 means "a little".
****공부 alone is a noun meaning "studies". 공부하다 means "to study". In English, the noun and verb form of a word are often the same. But you must be aware of the difference in part of speech in Korean. ("drink" is both a noun and verb. "I'm drinking a drink")(In Korean (운동 - exercise (noun); 운동하다 - to exercise (verb))