linux - server with high CPU and memory usage

I have a server with one WordPress website on it, but the resources of the server is almost finished. please check the image:

Where should i start to figure out the problem? should i get a server with higher resources ?

The server has one website with 600MB DB and about 900 visits per day
Some details about the server:

- mpm prefork

    

    StartServers            100
    #StartServers            10
    MinSpareServers         100
    MaxSpareServers         400
    MaxRequestWorkers       800
    MaxConnectionsPerChild      800

    ServerLimit         800

2- my.cnf

 key_buffer      = 1G

key_buffer      = 512M


max_allowed_packet= 512M

max_connections = 10000

max_connections = 1000

innodb_buffer_pool_size = 10G

innodb_log_file_size = 10G


innodb_file_per_table = 1

innodb_autoextend_increment=256

innodb_buffer_pool_size=10G

innodb_buffer_pool_instances=4

innodb_buffer_pool_instances=2


innodb_log_file_size = 104857600

innodb_log_files_in_group = 5

innodb_log_buffer_size = 268435456

innodb_io_capacity = 10000

innodb_io_capacity = 1000


thread_cache_size       = 16

thread_cache_size       = 8



key_buffer              = 16M

max_allowed_packet      = 16M


thread_stack            = 192K

thread_cache_size       = 16

thread_cache_size       = 8

query_cache_type        = 1

query_cache_limit       = 20M


query_cache_limit       = 10M

query_cache_size        = 100M

query_cache_size        = 50M



tmp_table_size      = 512M


table_open_cache_instances  =   16


slow_query_log      = 1

slow_query_log_file = /var/log/mysql/slow.log

3- meminfo

    MemTotal:       32459956 kB

MemFree:         6863712 kB

MemAvailable:   13162120 kB

Buffers:         1393928 kB

Cached:          5670744 kB


SwapCached:        39276 kB

Active:         20290788 kB

Inactive:        4120816 kB

Active(anon):   17336008 kB

Inactive(anon):   973836 kB


Active(file):    2954780 kB

Inactive(file):  3146980 kB

Unevictable:           0 kB

Mlocked:               0 kB

SwapTotal:       1046520 kB


SwapFree:         240992 kB

Dirty:              9088 kB

Writeback:             0 kB

AnonPages:      17307716 kB

Mapped:           263800 kB


Shmem:            962912 kB

Slab:             742360 kB

SReclaimable:     601588 kB

SUnreclaim:       140772 kB

KernelStack:        9760 kB


PageTables:       179828 kB

NFS_Unstable:          0 kB

Bounce:                0 kB

WritebackTmp:          0 kB

CommitLimit:    17276496 kB


Committed_AS:   33425764 kB

VmallocTotal:   34359738367 kB

VmallocUsed:      329084 kB

VmallocChunk:   34358947836 kB

HardwareCorrupted:     0 kB


AnonHugePages:     20480 kB

HugePages_Total:       0

HugePages_Free:        0

HugePages_Rsvd:        0

HugePages_Surp:        0


Hugepagesize:       2048 kB

DirectMap4k:      295140 kB

DirectMap2M:    15108096 kB

DirectMap1G:    17825792 kB