Hi,Unfortunately without a vet examination it is difficult to determine if a dog is pregnant or not at least until she is close to giving birth. At 30 days the vet can typically palpate the stomach and determine if she is in fact pregnant. You can do this as well, have her lay on her side and gently palpate the stomach area. You should feel round hard lumps in and around the lower stomach area.The nipples also enlarge as she gets further along as well as some weight gain. You typically will not notice much gain at all until a couple of weeks before delivery. You may notice her sleeping more or being more clinging though some dogs do not. Urination will increase the further she gets along as well as appetite increases. About a week before she is going to go into labor you can normally feel the puppies moving around and this is a indications she is in fact pregnant. I would advise a vet visit for a ultrasound or xray to determine how many puppy's you will be expecting. This is important for a couple of reasons.....the first so you know when she is done. Also if she has any trouble and her labor stops you will know if there are any more puppy's and to take her in. The second reason is so you can begin finding homes for the litter. This will give you time to check out the homes and ensure your new puppy's are going to good homes.
Since pugs typically have very difficult labors due to the size of the puppy's heads it is recommended that you have her xrayed regardless due to her breed. This will allow for you to set up a plan with your vet about when to come in should she have problems. Since pugs routinely require C sections for successful births I would recommend a vet who has a 24 hour office or a emergency office.Congratulations on your new litter. If you have any questions please feel free to let me know.