I recommend Ella. It's terrific and not too expensive. Several people on EF had their first successes with it. Or try a glass toy like the Deep Water G or, if you like larger toys, Icicles 17 or 18. All of these are terrific.
Focus on the sensations. Don't worry or stress if you're not successful just yet. Make sure you're well hydrated. If possible, try in places where you don't have to worry about whether you're about to pee, like the edge of the bathtub or with several folded towels under you. It also helps to start with some clitoral stimulation.
Good luck and keep trying.