Your DPS is low even for a new player. You need to get more DPS, not to trivialize bosses, but rather to stop making them unnecessarily harder. It'll be a more pleasant run for you and your supports. In any given random dungeon, it's actually pretty unlikely you're running with a super experienced support or tank that's at the top of their game. Not only are the far less common, but they're also less likely to queue in group finder.

As far as expecting buffs or not from supports? Yes, you're right that you can expect some buffs from even new healers! But the crucial thing is you can't expect a tank or healer at a basic vet dungeon level to have good enough up time to make a significant difference in your DPS. Consider that you, as a DPS, are still learning how to have good up times on buffs and your DOTs. A healer has to learn how to do that, while at the same time keeping you and the tank alive. It's a similar case for tanks, who have to control boss and stay alive. Remember, the primary role of tanks and healers is to tank and heal, not to buff - buffing comes second. New players are still learning to do that. Not to mention that many of the more powerful buff sets are from harder content that you and they are not ready for.

Also, let's look at some specific buffs and why they might not be used or have terrible up times for you.

Aggressive Warhorn is a common tank and healer buff ult. But it's hard to unlock for PvE players (need to do a bunch of PvP) so just based on that, I wouldn't expect new supports to have it. Even if they do, newer players will likely prioritize healing or defensive Ults to stay alive or keep the group alive. Also a DPS with low Crit won't get any benefit from it either, BC it increases Crit damage.

Combat Prayer gives Minor Berserk, and is an important healer skill. Except, it's a targeted AOE in front of the player. New players often move around a lot, making it very hard to get good up times on it.

Igneous weapons gives a powerful buff: major sorcery and brutality. Except almost no DK tanks use it! Why? Because DPS are expected to (and can) obtain that buff by themselves. But if you're not running a skill that gives that buff, you're missing out.

Ele drain is a commonly used skill that gives more resources to players, and actually, this will get called out a lot if it's not there. Simply because it's often quite easy to recognize the lack of resources when it's not being used. But the healer might have gotten the wrong morph, or just not be too good at keeping it up. And it won't do that much for your damage either, not by itself.

Many other buffs are from gear sets. Some might not be used because the player needs (or wants) the extra heal or survivability, or for utility, or simply it's not available to them yet.