Getting my 2 1/2 year old to stay in bed? Help!!!?

My son has been in a toddler bed since he was about 26 months because we were potty training him and he did fine with the transition but we couldnt get him to stay in bed. I read that maybe he was scared so I did someones suggestion to lay outside his door on the door so he could see me. I have done that since 26 months and it has always worked. He is now 32 months. At 26 months we started out with our legs in the door...then we started out moving to where we were in the hall then we moved to where we were in the hall but he could only see our legs. I was able to lay down and cover up so he saw me then id slide out and he wouldnt know since he could usually only see my legs. He use to go to bed at 8pm but during daylight savings time in april I had to move it to 9pm which i didnt really like. But he wont stay in bed or go to sleep even while we are on the floor. Im going to try an 8:30pm bedtime to see if maybe he is just over tired but idk. I am pregnant and the baby is due mid july. id really like to not have to stay on the floor every night if i can help it. I will not close him in his room so please dont tell me to do that. Also the past 3 nights is when he first started not going to sleep right away when i lay on the floor. So its new for us. He will lay down then call for us and get upset if we dont answer. Please help. Thanks