Strange that we seem to agonise so much over wind.
This is something that not all cultures do.
Wind can be a sign that your intestinal flora are working well.
If your diet is causing wind, then try not to worry about it
Use to be a Northern saying:
"Where ere ye be let the wind blow free".
The constipation may well be due to both reduction in bulk and the low carb diet.
I find that when I am eating high protein and low carb I get constipated.
I try and manage this by eating a few evening meals a week which are heavy in beans and pulses.
Although these cause the dreaded wind they also keep me going.
A good dahl will cure almost anything.
As already mentioned, not enough water can bung you up.
Not enough oils and fats in your diet can also bung you up.
I keep meaning to try a small glass of extra virin olive oil a day to see if that improves things; some people swear by it.
Extra exercise such as brisk walking can often free you off as it works the gut muscles as well as all the others.
As othere have said, don't worry about the variable rate of weight loss; most people can quickly lose at least 4 lbs with minimum effort but then the body starts to resist and the weight loss slows down.
Also remember that if you up your exercise you are likely to gain some weight because muscle weighs more than fat.
The weight loss should then resume (I hope - I've just put on 2lbs after spending a few days doing heavy work in the garden and restarting my 4 mile walks along the prom).
So - weight loss is variable but you are heading in the right direction.
Constipation is often a result of a change in diet. Your body should adjust after a while.
Cheers
LGC