Telling if a sugar glider is pregnant can be a really hard thing to tell, even after to joey's are born and crawl in the pouch. Different glider's act different. Truthfully, with my female, I can never tell until she has to little lumps that get bigger and bigger. As far as play time, my rule of thumb is, if she wants to play, play, and if she wants to be left alone leave her alone. The biggest thing right now even if you think she might be pregnant is to keep the stress level down, and make sure she's on a good diet. My female is carrying joey's right now and I try to limit her time out of the cage because she tends to get stressed when she's out, don't get me wrong she enjoys it but, shes very skittish when she has joey's.Just try to keep things normal without stressing her out, so play with her like normal but, keep a close eye on how she is acting.
There's no signs to look out for other than the lumps that appear. Before a suggie is due to give birth you may see her cleaning her pouch more, and then JUST before the birth you may see her licking a trail from the cloaca to the pouch, but other than that there is no way of knowing.
As for out of cage time, stick to the routine she's used to, stress can cause suggies to reject their joeys, a change of routine CAN stress them out! Also if you suspect she is pregnant then be careful when handling her, if a new born joey is dislodged from the nipple it will die, and it's also likely to cause some discomfort and possibly injury to mum too.