I recently found out it is actually pretty common for trans women to believe they have a period. This post comes from a place of love and concern, and I encourage everyone to read it, because honestly I'm frustrated how many people do not understand how menstruation works, including people who experience it.
If you do not have ovaries and an uterus, do not write off any abdominal pain as period cramps.
Period cramps are NOT a hormonal thing. I'm sorry, but no matter how long you take hormones you just won't have a menstrual cycle unless you are specifically altering your dosages to mimic this.
Prostaglandins are found everywhere in the body, but specific ones do specific things. Menstrual cramps are caused by prostaglandins that are released FROM the uterus to target the smooth muscle IN the uterus, causing contractions, similar to labor. It works locally, which is why things around the uterus can be affected, like the digestive system (cause of the infamous "period poops"). This is the specific prostaglandin that causes cramps:
You can see on the hormone graph that progesterone decreases before the bleeding period of the cycle. Progesterone and "the menstrual cramps prostaglandin" have an inverse relationship; when progesterone lowers right before the bleeding is expected to start is when people usually get cramps because there's no more progesterone to inhibit it.
Periods only happen because these hormones fluctuate. I've seen people say that trans women have periods because periods don't require bleeding. While it's true you don't need an uterus and the subsequent bleeding to have a period, you do need ovaries secreting fluctuating hormones. You can mimic this by changing the dosages of your hormones, though I don't know why anyone would want to, but you just cannot experience "period cramps" without an uterus.
This is why hormonal birth control works. A trans woman taking the same dose of hormones on a schedule is the same as me taking hormonal birth control pills every day and skipping the placebo week. Hormone levels are stable, so ovulation, and therefore, the period, is not triggered.
Hormones can do amazing things, but they are not the only things at play in a body. They cannot make an organ you do not have contract. This is why I am concerned. If you have recurring pain in your lower abdomen, do not ignore it. It could be something simple like constipation, but it could also be something serious like a hernia, infection, cancer, etc. Colons seem to love being able to have a million issues and narrowing down what that issue is could take a while, so you don't want to waste any time by dismissing this as period pain if you do not have an uterus.
Additionally, I will link this post of mine here. Everyone, people who have periods themselves or not, is guilty of perpetuating the normalization of "PMS," which does not exist. Normal hormonal fluctuations in the menstrual cycle should not have more of an effect on your mental state than "if I'm uncomfortable obviously I might be irritable." Of course things like dysphoria might make your mood worse, but that is not from the hormones themselves. As someone who has this set of parts, I have always hated this idea and how it is used to dismiss half the population's emotions for half the time, as well as used by people who have periods to subconsciously avoid accountability over their behavior by blaming it on their period. It's misogynistic and patronizing. I'm not a fan of people who do not have periods insisting they get them because of mental changes like this.
Other than cramps, hormones can cause all sorts of physical changes that you might attribute to period symptoms, like headaches or changes in energy, but these are side effects of taking hormones. The same things can happen to a body with ovaries that takes estrogen and progesterone. I had to stop taking hormonal birth control because it killed my body. Bodies can just be difficult about synthetic hormones.
TLDR: If you do not have an uterus, you cannot get cramps, so if you experience lower abdominal pain that doesn't go away, go to the doctor. If you do not have fluctuating hormones, you do not experience periods. Normal menstrual cycle hormonal fluctuations do not change your mental state or moods, so if that happens there is an issue that needs addressing (depending on your situation this one might take some fighting because many doctors dismiss PMDD symptoms as "normal PMS," which is an ancient misogynistic idea originating from "female hysteria").
All that said, I want to remind everyone that working to destroy the cisnormative idea that woman=period does not just help people who have periods and are not women, it also helps women who do not have periods. Many women do not have periods for various reasons. Trans women don't have periods and that is OKAY. Woman does not mean period. It's okay not to have a period. Please take care of the body you have, not the body you want.