TMI Scared to have sex with boyfriend!? 21weeks💙

I haven't let my boyfriend have sex with me since I was about 8-10 weeks pregnant! I still give him oral tho! Tomorrow I'm wanting to "surprise" him! BUT I'm worried about our baby boy! I don't want to rock or shake him while having sex ☹️ my boyfriend loves doggy style! I was just thinking of getting on top and doing the "cowgirl" position! Any helpful tips to keep it safe for baby??? PLEASE