3 Wan 2 LAN Balance failover and separate networks.

Hello guys, first sorry for my bad english! im doing this reading various guides and the wiki, still cant find anyone with this problem, or either other users use 1 lan, or 1 on 1 wan/lan distribution
I have a problem with this:

I got 3 wan connections that is should distribute 2:2:1 ratio
and i got two separate LAN and they never have to communicate with each other.
i got 1 rb750 to do the balance and distribution, and the two lan connections are managed by two rb1100ahx2 ( previous network administrator created two physical networks instead of vlans)


Thanks!

TL;DR: I want balance and failover with the 3 connections to the 2 lan.

/interface ethernet
set [ find default-name=ether1 ] comment=Alumnos
set [ find default-name=ether2 ] comment=Admin disabled=yes
set [ find default-name=ether3 ] comment="Fiber 6M" disabled=yes
set [ find default-name=ether4 ] comment="Fiber 50Mv2" disabled=yes
set [ find default-name=ether5 ] comment="Fiber 50Mv1" disabled=yes

/ip address
add address=10.103.100.10 comment=6MBFiber interface=ether3 network=10.102.100.10
add address=10.103.100.20 comment=50MBFiberv2 interface=ether4 network=\
    10.101.100.10
add address=10.103.1.3 comment=50MBFiberv1 interface=ether5 network=\
    10.103.100.10
add address=10.0.0.250/24 comment="Salida a Alumnos" interface=ether1 \
    network=10.0.0.0
add address=192.168.0.250 comment="Salida a Administracion" interface=ether2 \
    network=192.168.0.250

/ip dns
set servers=199.85.126.20,199.85.127.20

/ip firewall address-list
add address=10.101.100.0/24 list=Conectados
add address=10.102.100.0/24 list=Conectados
add address=10.103.100.0/24 list=Conectados
add address=10.0.0.0/24 list=Conectados
add address=192.168.0.0/24 list=Conectados
add address=192.168.0.0/24 list="Lan ADMIN"
add address=10.0.0.0/24 list="Lan Alumnos"

/ip firewall mangle
add action=mark-connection chain=input in-interface=ether4 \
    new-connection-mark=in_fiber50v2 passthrough=no
add action=mark-connection chain=input in-interface=ether5 \
    new-connection-mark=in_fiber50v1 passthrough=no
add action=mark-connection chain=input in-interface=ether3 \
    new-connection-mark=in_fiber6m passthrough=no
add action=mark-routing chain=output connection-mark=in_fiber50v1 \
    new-routing-mark=Out_Fiber50v1 passthrough=no
add action=mark-routing chain=output connection-mark=in_fiber50v2 \
    new-routing-mark=Out_Fiber50v2 passthrough=no
add action=mark-routing chain=output connection-mark=in_fiber6m \
    new-routing-mark=Out_Fiber6 passthrough=no
add action=accept chain=prerouting dst-address=10.102.100.0/24 in-interface=\
    ether2
add action=accept chain=prerouting dst-address=10.101.100.0/24 in-interface=\
    ether2
add action=accept chain=prerouting dst-address=10.103.100.0/24 in-interface=\
    ether2
add action=mark-connection chain=prerouting dst-address-type=!local \
    in-interface=ether2 new-connection-mark=in_fiber50v2 passthrough=yes \
    per-connection-classifier=both-addresses-and-ports:5/0
add action=mark-connection chain=prerouting dst-address-type=!local \
    in-interface=ether2 new-connection-mark=in_fiber50v2 passthrough=yes \
    per-connection-classifier=both-addresses-and-ports:5/1
add action=mark-connection chain=prerouting dst-address-type=!local \
    in-interface=ether2 new-connection-mark=in_fiber50v1 passthrough=yes \
    per-connection-classifier=both-addresses-and-ports:5/2
add action=mark-connection chain=prerouting dst-address-type=!local \
    in-interface=ether2 new-connection-mark=in_fiber50v1 passthrough=yes \
    per-connection-classifier=both-addresses-and-ports:5/3
add action=mark-connection chain=prerouting dst-address-type=!local \
    in-interface=ether2 new-connection-mark=in_fiber6m passthrough=yes \
    per-connection-classifier=both-addresses-and-ports:5/4
add action=mark-routing chain=prerouting connection-mark=in_fiber50v1 \
    in-interface=ether2 new-routing-mark=Out_Fiber50v1
add action=mark-routing chain=prerouting connection-mark=in_fiber50v2 \
    in-interface=ether2 new-routing-mark=Out_Fiber50v2
add action=mark-routing chain=prerouting connection-mark=in_fiber6m \
    in-interface=ether2 new-routing-mark=Out_Fiber6

/ip firewall nat
add action=masquerade chain=srcnat out-interface=ether3
add action=masquerade chain=srcnat out-interface=ether4
add action=masquerade chain=srcnat out-interface=ether5

/ip route
add check-gateway=ping distance=1 gateway=10.103.100.1 routing-mark=Out_Fiber6
add check-gateway=ping distance=1 gateway=10.103.100.3 routing-mark=\
    Out_Fiber50v1
add check-gateway=ping distance=1 gateway=10.103.100.2 routing-mark=\
    Out_Fiber50v2