Birthcontrol

There is no type of birth control that does not give side-effects. :/ The reason is because birth control pills are inherently altering the body's natural responses.

Indeed that's true. Essentially you are altering the body's hormonal response to releasing a mature egg for procreation. I think most of the weight gain comes from regular fluid retention. Estrogen in high doses is known to cause weight gain especially that due to fluid retention. The more estrogen there is in a pill, the more tendency to gain weight such that a 50 mcgm pill will result in more weight gain than a 35 mcgm pill. The mechanism of action is probably direct stimulation by the estrogen in pills of kidney substances called renin-angiotensin that cause water retention. The water retention then causes sodium (salt) retention. A lower estrogen level pill, for example 20 mcgm, will help reduce weight gain due to fluid retention.

Using the lowest possible estrogen containing birth control pill should minimize weight gain and swelling from water retention. Current 20 mcgm pills which are the lowest estrogen doses available are:

Alesse
Levlite
Loestrin-Fe
Mircette

do know which birth control is better?

According to clinical trials, triphasil does not cause significant weight gain, so that's probably your safest bet, but it varies from person to person.

I agree with biology101. Triphasil is your best bet, but just be cautious

By saying to be cautious what do you mean?

It really depends on the pill and the person taking it. There are lower dosage pills that still help prevent pregnancy, or work against acne if that's what you're using it for. The lower dosage lowers the intensity of symptoms or can get rid of them all together.

There are some people who will always experience symptoms from a bc pill or some people (like my friend) who get none whatsoever.
I'd say talk to your doctor about all the pills and the symptoms and maybe he can find a correlation between them and prescribe you something better.