Tel your OB/GYN... he/she will have a more conclusive answer for you.... sometimes its the baby putting pressure on us internally as they grow... or normal body pains as the body changes to accommodate the pregnancy, or the baby could be dropping.
There is no way for us to know for sure... that's why, ask your Doctor, first & only he/she would know your pregnancy status.
Also mention to your Doctor about your milk production, as you mentioned in your other posting. Do NOT stimulate your breasts or play around with it, as this can cause contractions. You don't want that, yet.
Make sure you know what "braxton hicks" contractions are, and the contractions you get prior to delivering... also ask your Doctor WHEN you should go in to the hospital and call him/her per any contractions you feel... and HOW you should time it, per going to the hospital.
ANY questions you have, ask your Doctor... since this is your first pregnancy/birth. Ask what you should do, and when and how to prepare... and when to pack your hospital bag!
All the best,
Susan