If i have never had a period, because i was born without ovaries and a uterus, would that cause me to gain weight and make it hard to lose weight?

Probably not: Eat a balanced diet and exercise more than you eat and you should be able to lose weight . Write down everything you eat. You are probably eating more than you think

No but: Having no uterus and ovaries does not affect weight loss or gain directly, but the reason (diagnosis) why they are missing might - do you have a diagnosis from your doctor?