I have multiple fibroids (few in my womb and some near my spine) and was intended to go for open-hole surgery and it was then I was diagnosed pregnant at 8 weeks. My gynae forewarned me of the risk but it is not life-threatening so it was okay to continue with the pregnancy.
Most of the fibroids are between 2-3cm. During my pregnany, some merged together and as a result, there are 2 extremely large fibroids (8cm and 11cm)in my womb and my tummy looks exceptionally big. I was not given any special medication but was closely monitored by my gynae each time I went back for scans/checkups. Was told I might have a premature baby or even a c-section if the fibroids have grown and obstruct the growth of the baby.
I am blessed that throughout my pregnancy, I did not have gestational diabetes (I am an anaemic with blood pressure reading usually 100/80 or 105/90 of the times), I work until 1 day before I admitted myself to the hospital to deliver my baby. In fact, my baby is overdue by 4 days from EDD.
Now, my baby is +13 months old, she is not chubby but growing up healthily and eating well.
In my last fibroids scan in February, my gynae told me that the sizes of these fibroids have became smaller and some have disappeared. If there is no pain, I could have just leave them there w/o having to go through an operation to get rid of them.
You must have some faith/trust in your gynae. If you have doubts, either clarifiy and get to know more from him/her or switch to another gynae whom you can trust and feel comfortable with to discuss about your problems.
Stay happy, dont't think about the fibroids, I believe both you and your baby will be good.
P/S: 33 years old is not to old. I am a few years older than you when I conceived ;-)