If you want to learn to tumble, you have to put in the time. Going to a class once a week probably won't get you there any time soon. Get to the gym as often as you can and listen to your coaches. Don't just nod and then forget what they say but actually try to use their comments and progressions into your next attempt.
Follow proper progressions. They build on each other. Can you walkover?? You need the shoulder flexibility from walkovers to do a good BHS. There is a reason you are progressed from skill to skill. It's safer and you're less likely to get injured but it also helps with your fundamental skills for more advanced tricks.
Condition. You can't tumble if you're not strong. You need strong legs, core, everything. If your coach tells you to condition, do it. Your tumbling will only improve. If you coach gives you drills, do them. They help you strengthen your body and teach you the muscle memory to do your skills properly.
Stop worrying about where your friends are or what they can do. Everyone progresses at different times. You may pick up skills faster then they did, or it may take you longer. And forget about cheer levels. Your tumbling alone will not place you on a certain level. Your stunt skills need to be there too. Even if you get your BHS, if you can't stunt at level 1 it wouldn't be safe for you to join a level 3 or 5 team. Trust that your coaches know where to put you to challenge you while keeping you at a peel that's safe and appropriate for you
