As has been said above, there are a lot of reasons for lack of libido, both for men and for women. Libido does natgurally hit highs and lows.
However in your case, I do notice that you mention your failure to reach orgasm. To have sex without an orgasm is like buying ice cream and never being allowed to taste or eat it. Eventually you will stop buying the ice cream.
It is important that you start to relax during sex, and start to allow nature to take over during sex, and not concentrate on your performance. Take it easy and have fun, and before you know it the climax will be there.
There is a great product called Provestra that will help you to get your libido back and will also help you on your way to a better and more fulfilling sexual encounter.
It would also possibly help for you and your boyfriend to explore some new techniques and possibilities in regard to sex positions and play. Try the new sex positions that get sent to via SizeGenetics.