First of all I appreciate your frankness I admitting your problem and asking for solution.
That itself is a welcome situation and it shows that you can amend and improve. A good start.
Now, let me say that whatever you feel is not a very big problem as you feel now, and most of the people would have similar problems and they would have got it solved gradually by life experiences or by getting help and advise from others.
You are young and naturally you lack experience of life. We all have come by experiencing various situations in life. Then we come to know where we are wrong and how to correct it. You also would do that similarly.
The positive part is that you are now pro-active. You know your problem, but want guidance to solve it. It will appear very easy to you when I cull it out from your own question above, and present it in simple words before you.
1. At first you are happy with others then, "start finding negative sides of them as time proceeds.".
Reason; fatigue out of familiarity. Old quote is" Familiarity breeds contempt".
Solution: You need to nourish and maintain relations. You have to know each other slowly and steadily only. Do not finish that in one day or one week. This will be needed throughout your life in any relation that needs to be maintained long. Involve them and introduce them to your other friends and realties. See only their positives. Do not give too much attention other negatives. Spend regulated time with them. Spread your time with others also and for your on other needs.
2." I tend to feel jealous and insecure in the group."
.Jealousy is not your monopoly. Most persons have it. But many outgrow it.
Reason: Jealousy comes from lack of self confidence and lack of achievement. It comes from avoidable comparison with others.
Solution: For this you have to work hard in one or two things and get expertise and excel in that. At the very first, stop comparing you with others. Accept that each one is individually unique and have separate space and opportunity. Let each one shine in their on field. You select your field and shine in that. But for that you have to put sincere and focused efforts In other fields you enjoy others excellence and openly appreciate them. Then that will become mutually appreciating and helping and supporting. Jealousy will automatically vanish. Of course theoretically it is easy. It needs sincere and constant practice. You can do it if you are open in mind and heart..
3. " I feel less comfortable with the people who are more qualitative (in terms of anything like personality, confidence etc."
Reason: Lack of self confidence.
Solution: Accept that each one have their own path, space and achievement. Believe in yourself, have confidence, have faith in destiny or God, pray, but work hard.
Follow the quote" Pray to God, Oh sailor, but row towards the shore.". Philosophise like Bhagavat Gita
" Karmanyevaadhikaarasthe ma phaleshu kadachina".
4. " I can't handle it if somebody is giving advice to me."(You have to stop this attitude immediately)
Reason: Your lack of experience. You are like a 'frog in the well'. You are not aware of the larger lakes and seas outside and away from you. Your world is short like a small pond.
Solution: We expand our world from reading, from experiencing ourselves, and from others experiencing. Advice from others constitute the last of the three. It is like chewing a readymade tablet than the laborious and tedious process of making a medicine ourselves. Always listen to others advice patiently at least till you get your own. You need not follow their advice immediately or word by word. Keep it in mind. It will come handy when you need it. If you shun experienced people, they may not come to your when you may really need them.
Mix with people who are knowledgeable, experienced and elder to you along with your own peers. More friends and more familiar people will expand your horizon and you will automatically come out of your cocoon. But be always prudent and know ho to take care of you from being cheated also. Observe and get help from you own parents and elder relatives also. After all they are your first well wishers.
All the best.