sex should be a mutual thing, both of you should want it at the same time else it will not be fully enjoyable to either party. forced sex is rape even if it is forced by your partner! remember you always have the right to say no!
the best way around any anxieties you have is to talk them through with your partner before sex is in the picture, if they are not willing to go at your pace then they are not worth bothering with. there are many more 'fish in the sea' who will treat you the way you wish to be treated.