Monitor tablespace size with increment by

Hi
I am facing the following problem. I want to monitor the size of tablespaces in my system. We have Oracle 9 and Unix operating environment. The tablespaces are autoextensible. Until now I used the following query and have a table which give some info
create table TblSpc_Tot
(
Tblspc_name VARCHAR2(30),
sumtot NUMBER(10,2),
summax NUMBER(10,2)
);

create table TblSpc_Free
(
Tblspc_name VARCHAR2(30),
sumfree NUMBER(10,2)
);

insert into TblSpc_Tot (Tblspc_name, sumtot, summax)
select tablespace_name,sum(bytes)/1024/1024,sum(maxbytes)/1024/1024
from dba_data_files
group by tablespace_name;

insert into TblSpc_Free (Tblspc_name, sumfree)
select tablespace_name,sum(bytes)/1024/1024
from dba_free_space
group by tablespace_name;

select t.tblspc_name table_name
,t.sumtot table_size
,f.sumfree used_rows
,t.summax max_bytes
,(1-f.sumfree/t.sumtot)*100 used_rows1
from tblspc_tot t, tblspc_free f
where t.tblspc_name=f.tblspc_name
order by (1-f.sumfree/t.sumtot)*100 desc;

The problem is that I do not use the info of the field increment by from the table dba_data_file so I do not catch the possibility of those tablespaces that can no
longer autoextend with increment size specified for them. Of course in a separate query I can have this info ( select file_name, bytes/1024/1024 current_size_MB, increment_by*8192/1024/1024 autoextend_size_MB, maxbytes/1024/1024 max_size_MB
from dba_data_files
where bytes>(maxbytes*0.90)
and autoextensible = 'YES'
or bytes/1024/1024+increment_by*8192/1024/1024>maxbytes/1024/1024
and autoextensible = 'YES';)
But I can not find a way to combine all. Do you have any tip regarding my question or should make 2 different queries?
Thanks in advance for your help