Post-Tubal Ligation & Irregular Periods: Possible Pregnancy?

Question
I am a 36 yr old woman, who had tubal banding performed in March of 2010. During this procedure I also had a cold knife cone done for cervical cancer cells.
My periods were regular until September when they became spotty and didn't last as long as usual.  I am sexually active with my partner, and I have been wondering if I could possibly be pregnant. Recently I have been having lower back pain, lower abdominal aches, not sharp pain, tenderness in the abdominal area.  Are the tubal bands as effective as the routine "cut, burn and tie"?
I visited my G.P. yesterday and told her of my symptoms, and she took a blood test for pregnancy which resulted negative. I feel miserable, and have an aversion to certain smells. After I eat, I frequently don't feel well.  I'm a little confused about what's going on with me right now, and I would love to get some answers.

Answer
Tubal Banding definitely is not as effective as the routine way of ligature and cut method, so there is a chance that you could be pregnant, but we can't say for sure until you actually test positive for pregnancy. You never mentioned your LMP. Secondly the symptoms of pregnancy you mentioned are very non specific and it is not possible to say with surety whether you are pregnant or not based on these symptoms alone. Therefore this is my advice. Do not get worked up and wait for 10 days more. Then repeat the pregnancy test. If it is negative then you can relax, you are not pregnant. If want to be very sure just delay this test by another 4 days so that you will test a fortnight from the time you read this. This is the best you or for that matter anyone can do at this time. So be patient. You can try a few non pharmacological pain management techniques like

1. You can do cold compress for your back ache.

2. Use a hot water bottle to provide relief for the abdominal cramps.

3. Do deep breathing exercises for 15-30 minutes in the mornings and evenings. Follow this method. inhale and exhale deeply. Now close one nostril and inhale deeply through the other nostril. You must aim to fill up your lungs. Hold for a few seconds and now close this nostril and open the other. Now exhale fully through this nostril. Repeat this process. During this time try to empty your mind of thoughts. With practice you will be able do this really well.