Regarding pull-ups:

If you are a beginner, I recommend that you check out Buffdudes' youtube video on pull-up progression. I am at work now, and my employer blocked out access to youtube, therefore I can't link it. Are you doing bent-over rows, lat pull-downs, inverted rows (my trainer calls them reverse push-ups)? Strengthening your back muscles should help you with pull-ups. I started off on the assisted pull-up machine a year and a half ago and now I can do 6 muscle ups. Do not get discouraged and keep working out your back. Speak to your trainer about your roadblocks and he/she will help you find a solution. Think smart and problem solve :)

Regarding bench presses: Where do you feel you get stuck? Are you feeling any pain anywhere that is limiting your progress? If you feel your form is off, there are plenty of resource to correct that. My problems with bench presses has always been my wrist being weak and prone to injury. I've been stuck on 135 for over a month now because my weights can't support all the stress. I've been using wrist wraps and correcting my grasp to better distribute the weight. My last suggestion is that if you are truly struggling with form, then it is not a bad idea to decrease the weights you are using and practice good form until it becomes natural to you and then slowly increase the weights.

This may be a dumb thing but are you getting enough rest? Not getting enough rest is possibly the culprit of your huge dips in rep numbers, your mood and you being tired all the time. Otherwise, you just have to get used to feeling sore after workout :)

Alternatively, you can progress differently. There are 3 mechanism for muscle growth: mechanical/muscle tension, muscle damage, and metabolic stress. All three need to be elicited to maximise your muscle growth, but you can tweek your exercises should you wish to increase one over the other. Provided that you always do your exercises in good form, varying the tempo will increase tension (stress over time). Increasing the rest and decreasing resting time will increase metabolic stress. Everyone you know will tell you that you need to overload every week. I found it beneficial when I get stuck to change my workout in order to progress. So I can't do bench presses at 135lbs? I am gonna pick up some dumbells and do some dumbell bench press in order to prevent muscle imbalance.

As cheesy as this may sound, do NOT focus on the result but focus on your journey. You have only dipped your toe into bodybuilding and to be realistic, you will only start to see truly noticeable changes after a year of consistent training.