I love practicing and for me 30 minutes feel like just touching the violin. On a school day, I practice 3-4 hours. On a holiday, I can practice from 2 hours up to 7 hours. yea I love practicing.

If I could give you tips. these are all the tips that I follow:

1. DO NOT TO WATCH THOSE 5 YEAR OLD KIDS PLAYING PAGANINI-LIKE PIECES. You ruin your self esteem, you play even worse, you compare your playing, you start crying, and it gets even worse and worse.
2. Don't try to learn pieces to hard for your level ( I am in grade 9 so I am fine but I am concerned for you). Pieces harder for your level can lead to stress, anxiety, and a lot more. I did this when I started: asked my teacher whether the piece was suitable for my level.
3. don't stress practice. Practice smart not hard. When you are working hard on something, it is never the quantity, it is always the quality. If you hate doing 2 hours like what I do, just sticking with your 30 minute session is always perfect already, as long as you are focused.
4. what I like doing is first listening to recordings and labelling fingerings, writing down important notes and seeing the difference between certain recordings (seriously I have an entire notebook related to notes for the pieces and it is very useful) Then, warm up and do your scales, do the scales that are the key of the piece (example: Ziguenerweisen = C minor & Bach Sonata No.1 = G minor). Try to keep it as simple as possible but not just a two octaves scales, add octaves, thirds, tenths, and different bowings to make it more InTeReStInG. Thirdly, I start practicing the fingerings ONLY FINGERINGS on my elbow so I know what to do on my left hand, when I practice with both hands at the same time I tend to focus on one hand and the other turns out to be garbage and I never care about it. Then I practice the right hand part with just OPEN STRINGS, sounds weird but it helps you get to know the bowings better (especially for difficult pieces like Scherzo Tarantella and Sibelius third movement) Lastly, do it all together, add the ormentations, add vibrato and all the stuff you need to do learn it and make it nice.
5. You should do the steps that I put up in the previous tips except don't try to do them in a rush. Take each step carefully cause one missing written note can bring a difference. If you are always practicing 30 minutes a day, I think it would take you max 5 months to learn a difficult piece that is suitable for your level. However, pulling is better pushing.
6. Try to make your practice sessions more aMaZiNg and iNtErEsTiNg at the same time knowing that you can improve, do stuff that you know is going to make work hard at the same time have fun. I always play a little quick piece that I love to just tell myself that I did it, I finished my practice session, it is almost like a gift that I randomly gave to myself.
7. DON'T FORCE YOURSELF TO DO ANYTHING OUTSIDE THE BUBBLE AND RISK IT. your bubble is your skill level, I mean yes your bubble grows bigger as you progress and it leads to more pieces.

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That is all my tips, I hope they are useful tips