I have been on Wellbutrin XL 150 mg for about a month and a half....

I have been on Wellbutrin XL 150 mg for about a month and a half. I really do not feel any difference. I was put on it for mild depression and loss of energy, but I still feel like I am floating through my days and can't wait to go home and crawl into bed. I should also mention I am on a very small dose of beta blockers for my atrial fibrillation (which is meant to decrease my heart rate). Should I increase to the 300 mg dose? I am concerned about doing this, as this is my first time on any anti-depressant and I would eventually like to wean myself off. Also, have any women noticed their periods are late or non-existent? I am a week late in my period, and I am NEVER late. I will be going to get a pregnancy test done, but I am fairly certain I am not pregnant. I also noticed very heavy cramping yesterday that would signal the start of my period, but nothing happened. I would appreciate any feedback! Thank you.