Need advice to improve my body

First of all I want to clarify that English is not my mother language, so sorry for any possible mistakes and that it took me a while to write about everything that bothers me in my road to better my body and in the process myself. I will include a tl;dr at the bottom. I want to thank in advance anyone who will take a minute out of their time to comment any advice and try to help me.

I'm a male, 23 y.o., 1.84m/6ft, 72kg/158lbs. In summary I will describe myself as skinny fat. That is my main issue, a thing that bothers me since I was a kid, to the point it caused me an inferiority issue. I have so much fat for my kg, in my stomach and my upper legs and glutes. But in the other areas of my body I'm very skinny, especially in my face(My grandma saw me recently and told me that I should gain at least 3kg). My second issue, while it's connected to the first, is that I have very little of a muscle in all of my body, except maybe my legs (I used to play soccer and ride the bicycle). My chest is flatter than a wall and my arms are like a girl's. Third issue with my frustrations and really a direct result of the above is that I don't know what to do to achieve my goal, which is drop my body fat percentage and increase my muscles. I don't want something crazy, just a toned body.

I understand that the combination of diet and workout is the key but I'm clueless as to what to actually do which destroys my morale and motivation to continue. This includes both the gym and my diet.

I have a gym membership, now entering the 3rd year and I saw absolutely no results out of my workouts. Thing is because I don't know what to do I rarely went to the free weights room, I tried to only do the machines, most recently tried group courses like Body Pump and Body Combat usually had "injuries"(muscle fatigue, not being able to walk for a few days) all of which made me skip gym for longer and longer periods and then back from the beginning like a circle.

While on the subject of the gym, I took a free "body analysis" session that was provided by the gym where you stand barefoot in a machine while holding it with your hands and then it analyses your body fat and muscle percentages. I don't remember specifically the name of the company that made the machine and I don't know if/ how reliable it is but I got results that can basically be summarized as skinny fat (big fat percentage/ low muscle percentage). The weird part about this session though was that the nutritionist(?) who explained the results to me, stated that according to the test the amount of calories that I have to get everyday in order to maintain my weight were ~1550 and that as I get older that number is going to drop even lower. That was definitely something I was not expecting as 1500 calories seemed like too little for a man of my age and height. The advices the nutritionist gave me were things like eat healthy, a lot of fruits, and workout, so nothing specific, things that I already do or try to do.

Moving on my diet. I always try to eat as healthy as I can, I try to avoid sugar altogether as long as I can, eat fruits and vegetables. One thing that I lack and try to improve is that I don't drink enough water. My standard breakfast is a turkey and cheese toast with a glass of a fresh orange juice and a boiled egg. My lunch and dinner is something that I cant really control as I eat in a uni restaurant, but mainly consist of a main dish and a carrot/cabbage/lettuce salad. The main dishes often are chicken/patty/pork with white rice or roasted potatoes. There is also unlimited bread which depending on how much I'm hungry take 1-3 slices. I dont eat sweets or fast food, chips, cola etc. I used to count my calories with various apps but that lasted only for a few months because my friends made fun of me and the apps calories goal was off for me(?) 2500 calories for maintance etc.) Then I dont know which goal to choose. I understand that in order to lose body fat you have to take lower calories than the maintance level while in order to grow your muscles you have to do the opposite. Another thing that confuses me was what and when to eat, before or after a workout . So I what I do is just take a banana with me for after the gym.

All in all as you can see I am clueless as to what to do both in my workout and my diet aspect. I want to drop my fat percentage and increase my muscle one, have a toned body which I think will improve my self esteem and I'm willing to do what it takes both in the gym and in my diet but I don't know what to do and that damages my morale and will to continue. After all, how can you have will to continue when you don't know what to continue.

TL;DR: 23 y.o. male, 1.84m/6ft, 72kg/158lbs. skinny fat, supposedly have to take 1550 calories to maintain my weight, want to lower my body fat percentage and improve my muscle percentage but I don't know what to do as I get demotivated with injuries, not knowing what to do etc.