Ultrasound

Hello mommies would like to ask for advice if you are in my place. I have a myoma, i'm in my 25th week. Altho the OB told me it is far from my baby naman i wanted to monitor it sana from time to time so my question is okay lang ba na mag pa ultrasound ako every now and then like once a month? yung last CAS ako is when i was on my 20th week pero during that time hindi nagfocus sa myoma yung sonologist so hindi din nakita if lumaki ba or what and last check ko pa sa myoma ko was on my 16th week. Not that i'm super worried but one of my aunties kasi she had a myoma then she had a still born at 9months so unfortunately the baby died inside the womb but i'm just not sure if it's bcos of the myoma entirely. So is it okay ba if i will get ultrasound without my doctor's advice or referral?