Studying can be difficult without a clear aim of what you are working towards. It's OK to have a broad goal such as wanting to get over 90 on an exam but it's important to also have specific, small sub-goals of how you will work towards this! That way, completing said smaller goals can not only ensure you're making consistent progress towards the goal but it's also much more motivating knowing that you've checked off goals of how you will prepare for the test. For instance if it was Maths you may have a list of specific exercises / areas you want to work on and you can pick out specific practice problems to work through. Even if you can't achieve this (e.g. say a problem is too hard so it is incomplete), at least make sure you attempt the goals and work towards seeing them completed which you seem to be doing by asking your professor for extra clarification. So that's good!
Seeing quantitative progress of what you have achieved is satisfying but if you're finding it hard to meet goals - setting specific soft deadlines (e.g. needs to be done by the 12th of November) can be helpful rather than saying "I'll get it done sometime within the next 2 weeks!". Different techniques work for different people though and some people don't like a rigid deadline but at the very least, having small specific goals you want to complete by the end of the day or week can help you see what tasks need to be done rather than generalising that you need to study x hours a day for this subject, which is too broad to really work on and hard to meet without goals of what you want to achieve in the study session.
When trying to get into a studying routine, I also feel like it is often about discipline rather than motivation! Hopefully you do feel motivated as you've picked a course that you're interested in but if you're finding it hard to start, the five minute rule can be good to stop procrastination so that you don't end up with 27349324302 hours of work the day before the exam. You'll never feel 100% motivated to work most days but you can tell yourself you'll work on it for five minutes and that often encourages people to keep going rather than stopping.
I also feel like less is more - instead of aiming to study for hours a day if you haven't been doing that before, slowly build up a strong study routine. At the start you can tell yourself perhaps you just want to study with full concentration for an hour a day and then gradually increase the time increments (make sure you take breaks of course!). I know it could be discouraging if it seems like other people who don't study perform better on the exam even as you build up a study routine but it's always hard work that perseveres and not talent so keep going and you'll see a very visible improvement in grades.
I know final season is approaching but afterwards, I find it is also more important to ensure you do consistent, small time everyday to review over material rather than starting to study in the weeks leading up to the exam. It's a pain at the beginning but saves a lot of stress around exam season as you will have reviewed material throughout the term. Make it a goal maybe to ask yourself what you have learned and can you explain it concisely in your own words (either aloud or write down a summary?). Also I can not stress enough to focus on reviewing your weaknesses - it is easier to just hope it doesn't come up on the exam but only studying your strong points won't improve your grades unfortunately and you'll feel better covering all your bases. If you're not sure how to improve on a weakness it can be good to come up with points on what you would like clarified and then don't feel afraid to ask either a professor or someone who is good at the subject for some help! In terms of how to review it really depends on what type of learner you are - some people like making flash cards, other people like mind maps but generally for most people at least making it a goal to complete practice exams is a good approach as it will model what will be on your final and you can identify weak areas very quickly.
There are also apps you can get on your phone if you tend to get distracted or need an incentive to study. It's tempting to check your phone when studying as a quick break but dedicate your full concentration to the allocated time you've set for study - it's VERY easy to spiral into procrastination and it's much harder to regain focus. The past year when preparing for university entrance exams I tended to use apps like Forest which reward you for studying (and also have consequences for getting distracted / checking your phone) - if you're into video games, I've heard HabitRPG is also a satisfying one! There's a lot of apps like those out there and they can be very valuable. If studying by yourself gets monotonous, you can also consider just changing up the environment (e.g. studying in a library) or having a review session with friends who do the subject where you quiz each other. But most importantly, do take 5 - 10 min breaks every hour and use those breaks as a chance to stretch, get hydrated etc. It's a balance of working hard but do take breaks so that you can feel refreshed for the next study session - no one can work 24/7 without getting exhausted so make sure to prioritise your wellbeing too. Some days you really won't be able to find the energy to study and that's completely OK - however do make sure you do use something like a timer / incentive the next day to complete some work you don't lose a consistent routine.
I think the fact that you're actively trying to improve your studying routine is a great sign and that you're going in the right direction by seeking the help of your professors! Work ethic takes time to develop so don't feel too discouraged if your studying routine doesn't change overnight. Over time, it becomes a lot easier to get into a good routine. I'm sorry that I wrote quite a lot but as someone who just finished all their exams, this was a lot of what I picked up over the past few years. Best of luck. <3