Can I Piggyback 4 15 amp outlets off a 30 amp fuse?
Since the wire is 14/2, the breaker feeding it must be 15A.
Someone apparently changed that to a 20A breaker (presumably because they were sick of constant breaker trips every time they attempted to use two heat appliances at once). Since that was done, you have the sense of &quot;hey, do it even more&quot;.
That &quot;end justifies the means&quot; POV ignores the reason we use circuit breakers in the first place, which is to prevent house fires. The National Electrical Code specifies this based on hard data, and if you're not interested in following that, then this is the end of the answer for you. We can't help you on this site.
Your loads and why they are tripping
A 15A circuit (which you do have, even if it's horribly misbreakered) can accommodate 1800 watts.
A 20A circuit on #12 wire can accommodate 2400 watts.

Your refrigerator needs about 100 watts (trivial, don't need to give it too much thought).
Your air conditioner needs 500-1500 watts (whatever its nameplate says; it may be stated as VA).
Your toaster oven needs 1500 watts.
Your hot plate needs 1500 watts (some are less).
Your microwave needs ~1200 watts.

As you can see, you can run precisely one of these at a time on a 1800 watt capacity circuit (and you get to ignore the refrigerator). A 15A circuit can't handle two.
And you know a second thing: a 20A (2400 watts) circuit can't handle two, either. So bumping the breaker to 20A didn't actually buy you anything useful, it only brought 600 more watts, and that's not enough. Since the 20A breaker is illegal, dangerous and useless, change it back to 15A.
And I bet you didn't know any of this, and were just confused and frustrated by all the breaker trips.
Now, you can make a decision whether you can live with one at a time (refrigerator not mattering) or whether it's worth the blood sweat &amp; tears to bring more power to this room.
More power, please
For a modest power increase, I would bring up 12/3 cable, and wire it as a multi-wire branch circuit. This will yield two 20A circuits (2400 watt each). As we already established, you still can't run 2 things on the same circuit, except,

the refrigerator is no problem and
if the A/C is small, say, under 900W, then it can share a 20A circuit with a 1500W appliance.

So now, we can run the A/C, refrigerator and any two cooking appliances.
Bigger please? OK, run two multi-wire branch circuits, for four 20A sub-circuits. Everything at the same time, win!
Bigger still? OK. We'll need a subpanel. The next size up of wire is 10/3 which will give us 7200 -- oh heck, for the same price you could buy 4-wire #2 aluminum for 21,600 watts! Or for less money, #4 aluminum for 15,600 watts, or even cheaper #6 Al for 12,000 watts.
Now your subpanel will have power to spare, and you can give every appliance a dedicated circuit and use them all at once if you want to.
Both options are complicated and require a lot of knowledge, attention to detail and respect for the electrical codes, so best to hire a professional for the job.