Looks like the people commenting on your post aren't helping much at all. They're right-- what you're doing is pretty far from the generally accepted paleo idea/diet/etc, and I would recommend cutting fruit and including full fat in your meals-- but I also know that amenorrhea is a complex issue and possibly caused by a number of things. Most of which are not to be alarmed about, so breathe, sally, breathe!
First, rapid weight loss can mess up your menstruation, partly because estrogen is produced in your fat cells. I'm sure there are other hormonal effects of weight loss as well, especially if your diet changed in any way before beginning paleo, but I couldn't put my finger on one thing or another. Did anything get added to your diet? Deleted? Anything that is linked to hormones in research, such as dairy, soy, or conventional meat?
One problem that women often have with irregular periods is PCOS, Poly cystic ovarian syndrome. PCOS is diagnosed by the presence of cysts on the ovaries and perhaps a slew of other symptoms including acne, hair loss, and hair in typically male locations. PCOS has been tied--by even conventional wisdom doctors-- to insulinemia, high carbohydrate consumption, metabolic syndrome, etc. The theory is that insulinemia induces high testosterone levels and general hormone imbalance. In light of this information, doctors usually recommend that women lose weight to mitigate PCOS. However, there is still a significant portion of women with PCOS who are in good physical condition. I have no idea why. No idea. Clearly the hormone system is out of balance, but the question is: why? i haven't been able to find any research on the matter.
Secondly, whether your menstruation difficulty is due to weight loss or to PCOS, don't panic, because I promise (well, no, but I've been told its quite likely) you can still have babies. Even if you don't ovulate for years you can troubleshoot different hormone therapies with your doctor and get started menstruating again.
There are other reasons that you could have lost your period. They are much more rare, but also more serious. Good reasons all to get checked out by a good doc.
Sally I happen to know a lot about this because I think that I'm in a fairly similar situation. I stopped menstruating in November of 2009 (as I believe I stated above). That was preceded by rapid weight loss. I went Paleo in March 2010. Still at the same (healthy) weight, nothing changed. (I don't have much of a sex drive, either, note). In June, some Acne appeared, in September, even more, and to do this day I still have acne and I still don't menstruate. I got an ultrasound and it turns out I have cystic ovaries, but given that low carbohydrate diets are recommended to mitigate PCOS, there's not a whole lot more I can be doing.
I have tried all sorts of different foods. I eat very strictly paleo--saturated fats and fish and eggs and cruciferous vegetables. I have tried exercising less and exercising more, and eating different macronutrient ratios and... well, everything. Going paleo has cured me of so many problems-- insomnia, blood sugar swings, keratosis pilaris, hair loss, overweight-- but it has not cured me of this. Not yet. And there are a whole lot of variables to consider and weigh, and I don't even know half of them, both for you and for me, so I can't possibly make proper recommendations. I will 100 percent put myself behind paleo. I think its very important, and maybe it is helping. It has been shown to help many people. But hormone levels are definitely the place to start looking, and I would get tested. Its possible whatever you are dealing with is very far removed from your food choices. I'd go ahead and get behind your commenters, as unhelpful for your problem as they are, and say you might want to 'clean up' your diet and see if it helps. But I lost my period on a no-fat high-carb diet, and I didn't get it back on a high fat no carb clean paleo diet either.
And finally--you're doing great! Even though your diet isn't the most pristine paleo, you're on the right track, and you're going to figure out the problem with your periods in time. Don't sweat it. Asking questions and seeing doctors is the absolute best thing you could be doing. Way to go.