At first, I was all exited and stuff, did an RC like 15 times a day or more. But now I´ve given up. It just doesn´t work for me! I´ve been trying MILD every night for a couple of months and I´ve only had 3 LDs. And that makes me sad. Why can´t I become lucid? 
Your self-confidence is extremely important, and I get the impression that you don’t trust in your skills enough.
Also it’s very normal to lose motivation every now and then - heck, I had a decent LD the other day and even I don’t feel that motivated right now.
Stress can make you temporarily lose interest as well, because you might feel that you have a lot of important things to keep up with (like studying for an exam or something) - that’s how it is for me right now, I have several subjects that I need to finish in a few months, and I don’t feel comfortable with becoming too absorbed into lucid dreaming since it might distract me from studying.
First make sure that you really believe in yourself - then start living yourself into the imagination of what you would like to experience in your dreams.
One thing I often do is that I get up very early in the morning, walk outside and really try to imagine that everything around me is a dream.
It’s a fantastic feeling, and gives you a great foretaste of what lucid dreams can feel like, and I think this will boost your motivation a lot.
Try it. 
Many beginners also make the mistake that they are very impatient and want LD’s to happen almost instantly.
You will need to understand that this kind of thing requires practice - your mind isn’t used to being awake in your dreams, so you will need to practice being as aware as possible while you are awake, look for signs that prove you really are awake etc - basically, develop a questioning mindset, so you never take reality for granted.
Be aware about as much as possible around you whenever you feel you have the energy for it, ask yourself “why is this reality? Does anything here tip me off that I’m dreaming?”.
First of all, you are much better off than some of us. You have had lucid dreams in a fairly short timespan. If you think you need it, take a break. I got my first lucid dream after 1 year, and even then I had actually stop trying.
Relax and take it easy.
You’ve actually had three LD’s in a couple of months. That’s waaay more than most people have in the start of their LD “career”. But I understand. If you feel like having a break, just have one, but whatever you do, don’t do the same mistake as I did. When I took a break because of the lack of motivation, I stopped writing in my DJ. When i regained med interest on the subject, my DR was just patetic, and I’m still working on improving it…
I suggest you to go in the dream journal part of the forum, it helped me a lot and try to read a book about it.
You gotta convince yourself that ld are easy( im still working on that) and trust yourself, that helped me too