First time mommy ultrasound

Mayra
So I got sent by my OB to get a routine ultrasound next week when I'll be around 18 weeks. I'm just wondering is this ultrasound where I'll be able to see the gender, hear the heartbeat and get a lot of pictures of my little one? 
Everytime I would go see my OB I would have to sit there and watch videos for almost two hours before she would go in to see me and when she finally did the visit lasted about 3 minutes (no kidding). I feel like I haven't gotten reassurance that my baby is ok just because I haven't heard the heartbeat or seen much of him/her. Any advice would help. Thanks in advance!